Home
%3CLINGO-SUB%20id%3D%22lingo-sub-347422%22%20slang%3D%22en-US%22%3ETroubleshooting%20a%20simple%20error%20message%20using%20FREB%3C%2FLINGO-SUB%3E%3CLINGO-BODY%20id%3D%22lingo-body-347422%22%20slang%3D%22en-US%22%3E%3CP%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20%23333333%3B%20font-family%3A%20%26amp%3Bquot%3B%20segoe%20ui%26amp%3Bquot%3B%2Ctahoma%2Carial%2C%26amp%3Bquot%3Bhelvetica%20neue%26amp%3Bquot%3B%2Chelvetica%2Csans-serif%3B%20font-size%3A%2014px%3B%20font-style%3A%20normal%3B%20font-variant%3A%20normal%3B%20font-weight%3A%20400%3B%20letter-spacing%3A%20normal%3B%20orphans%3A%202%3B%20text-align%3A%20left%3B%20text-decoration%3A%20none%3B%20text-indent%3A%200px%3B%20text-transform%3A%20none%3B%20-webkit-text-stroke-width%3A%200px%3B%20white-space%3A%20normal%3B%20word-spacing%3A%200px%3B%20margin%3A%200px%200px%2010px%200px%3B%22%3EFREB%20(Failed%20Requests%20Tracing%20%E2%80%93%20formerly%20known%20as%20Failed%20Request%20Event%20Buffering)%20is%20one%20of%20the%20nicest%20features%20released%20with%20IIS7%20which%20would%20come%20in%20handy%20during%20troubleshooting.%20It%20does%20request%20based%20tracing%2C%20and%20produces%20a%20log%20file%20(in%20.xml%20format)%20that%20shows%20events%20and%20notifications%20from%20the%20various%20modules%20that%20worked%20on%20the%20request%20during%20its%20lifecycle.%3C%2FP%3E%0A%3CP%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20%23333333%3B%20font-family%3A%20%26amp%3Bquot%3B%20segoe%20ui%26amp%3Bquot%3B%2Ctahoma%2Carial%2C%26amp%3Bquot%3Bhelvetica%20neue%26amp%3Bquot%3B%2Chelvetica%2Csans-serif%3B%20font-size%3A%2014px%3B%20font-style%3A%20normal%3B%20font-variant%3A%20normal%3B%20font-weight%3A%20400%3B%20letter-spacing%3A%20normal%3B%20orphans%3A%202%3B%20text-align%3A%20left%3B%20text-decoration%3A%20none%3B%20text-indent%3A%200px%3B%20text-transform%3A%20none%3B%20-webkit-text-stroke-width%3A%200px%3B%20white-space%3A%20normal%3B%20word-spacing%3A%200px%3B%20margin%3A%200px%200px%2010px%200px%3B%22%3EThis%20is%20going%20to%20be%20a%20series%20of%20posts%20talking%20about%20using%20FREB%20during%20troubleshooting%20various%20scenarios.%20In%20this%20blog%20post%2C%20I%E2%80%99m%20going%20to%20cover%20few%20scenarios%20like%20troubleshooting%20a%20specific%20error%20message%2C%20and%20what%20to%20look%20for%20in%20the%20FREB%20output.%3C%2FP%3E%0A%3CP%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20%23333333%3B%20font-family%3A%20%26amp%3Bquot%3B%20segoe%20ui%26amp%3Bquot%3B%2Ctahoma%2Carial%2C%26amp%3Bquot%3Bhelvetica%20neue%26amp%3Bquot%3B%2Chelvetica%2Csans-serif%3B%20font-size%3A%2014px%3B%20font-style%3A%20normal%3B%20font-variant%3A%20normal%3B%20font-weight%3A%20400%3B%20letter-spacing%3A%20normal%3B%20orphans%3A%202%3B%20text-align%3A%20left%3B%20text-decoration%3A%20none%3B%20text-indent%3A%200px%3B%20text-transform%3A%20none%3B%20-webkit-text-stroke-width%3A%200px%3B%20white-space%3A%20normal%3B%20word-spacing%3A%200px%3B%20margin%3A%200px%200px%2010px%200px%3B%22%3E%3CSTRONG%20style%3D%22box-sizing%3A%20border-box%3B%20font-weight%3A%20bold%3B%22%3ETroubleshooting%20a%20simple%20error%20code%3C%2FSTRONG%3E%3C%2FP%3E%0A%3CP%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20%23333333%3B%20font-family%3A%20%26amp%3Bquot%3B%20segoe%20ui%26amp%3Bquot%3B%2Ctahoma%2Carial%2C%26amp%3Bquot%3Bhelvetica%20neue%26amp%3Bquot%3B%2Chelvetica%2Csans-serif%3B%20font-size%3A%2014px%3B%20font-style%3A%20normal%3B%20font-variant%3A%20normal%3B%20font-weight%3A%20400%3B%20letter-spacing%3A%20normal%3B%20orphans%3A%202%3B%20text-align%3A%20left%3B%20text-decoration%3A%20none%3B%20text-indent%3A%200px%3B%20text-transform%3A%20none%3B%20-webkit-text-stroke-width%3A%200px%3B%20white-space%3A%20normal%3B%20word-spacing%3A%200px%3B%20margin%3A%200px%200px%2010px%200px%3B%22%3EFirst%2C%20let%E2%80%99s%20take%20an%20example%20of%20troubleshooting%20a%20simple%20straight%20forward%20error%20code%20%E2%80%93%20HTTP%20400%20Bad%20Request.%20Whenever%20you%20get%20HTTP%20400%20Bad%20Request%2C%20the%20first%20thing%20to%20check%20is%20to%20find%20out%20where%20the%20HTTP%20400%20is%20logged%20%E2%80%93%20is%20it%20in%20IIS%20W3SVC%20logs%2C%20or%20in%20the%20HTTPERR%20logs.%20In%20this%20example%2C%20it%20would%20be%20in%20the%20W3SVC%20log%2C%20and%20that%20tells%20us%20that%20the%20request%20is%20actually%20processed%20by%20the%20IIS%20pipeline%2C%20and%20returned%20with%20HTTP%20400%20to%20the%20client.%20Only%20if%20the%20400%20is%20in%20IIS%20logs%2C%20we%20would%20be%20able%20to%20use%20FREB%20for%20the%20troubleshooting.%20Below%20is%20the%20sample%20screenshot%20of%20the%20error%20message%20(when%20browsed%20from%20the%20server%20itself%20%E2%80%93%20using%20localhost)%3A%3C%2FP%3E%0A%3CBLOCKQUOTE%20style%3D%22border-left-color%3A%20%23eeeeee%3B%20border-left-style%3A%20solid%3B%20border-left-width%3A%205px%3B%20box-sizing%3A%20border-box%3B%20color%3A%20%23333333%3B%20font-family%3A%20%26amp%3Bquot%3B%20segoe%20ui%26amp%3Bquot%3B%2Ctahoma%2Carial%2C%26amp%3Bquot%3Bhelvetica%20neue%26amp%3Bquot%3B%2Chelvetica%2Csans-serif%3B%20font-size%3A%2017.5px%3B%20font-style%3A%20normal%3B%20font-variant%3A%20normal%3B%20font-weight%3A%20400%3B%20letter-spacing%3A%20normal%3B%20orphans%3A%202%3B%20text-align%3A%20left%3B%20text-decoration%3A%20none%3B%20text-indent%3A%200px%3B%20text-transform%3A%20none%3B%20-webkit-text-stroke-width%3A%200px%3B%20white-space%3A%20normal%3B%20word-spacing%3A%200px%3B%20padding%3A%2010px%2020px%2010px%2020px%3B%20margin%3A%200px%200px%2020px%200px%3B%22%3E%0A%3CP%20style%3D%22box-sizing%3A%20border-box%3B%20margin%3A%200px%3B%22%3E%3CA%20style%3D%22background-color%3A%20transparent%3B%20box-sizing%3A%20border-box%3B%20color%3A%20%23337ab7%3B%20text-decoration%3A%20none%3B%22%20href%3D%22https%3A%2F%2Fmsdnshared.blob.core.windows.net%2Fmedia%2FTNBlogsFS%2FBlogFileStorage%2Fblogs_msdn%2Fwebtopics%2FWindowsLiveWriter%2FTroubleshootingusingFREBpart1_3129%2Fimage_2.png%22%20target%3D%22_blank%22%20rel%3D%22nofollow%20noopener%20noreferrer%20noopener%20noreferrer%22%3E%3CIMG%20width%3D%22458%22%20height%3D%22375%22%20title%3D%22image%22%20style%3D%22border-image-outset%3A%200%3B%20border-image-repeat%3A%20stretch%3B%20border-image-slice%3A%20100%25%3B%20border-image-source%3A%20none%3B%20border-image-width%3A%201%3B%20box-sizing%3A%20border-box%3B%20display%3A%20inline%3B%20height%3A%20auto%3B%20max-width%3A%20100%25%3B%20vertical-align%3A%20middle%3B%20border%3A%200px%20none%20currentColor%3B%22%20alt%3D%22image%22%20src%3D%22https%3A%2F%2Fmsdnshared.blob.core.windows.net%2Fmedia%2FTNBlogsFS%2FBlogFileStorage%2Fblogs_msdn%2Fwebtopics%2FWindowsLiveWriter%2FTroubleshootingusingFREBpart1_3129%2Fimage_thumb.png%22%20border%3D%220%22%20%2F%3E%3C%2FA%3E%3C%2FP%3E%0A%3C%2FBLOCKQUOTE%3E%0A%3CP%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20%23333333%3B%20font-family%3A%20%26amp%3Bquot%3B%20segoe%20ui%26amp%3Bquot%3B%2Ctahoma%2Carial%2C%26amp%3Bquot%3Bhelvetica%20neue%26amp%3Bquot%3B%2Chelvetica%2Csans-serif%3B%20font-size%3A%2014px%3B%20font-style%3A%20normal%3B%20font-variant%3A%20normal%3B%20font-weight%3A%20400%3B%20letter-spacing%3A%20normal%3B%20orphans%3A%202%3B%20text-align%3A%20left%3B%20text-decoration%3A%20none%3B%20text-indent%3A%200px%3B%20text-transform%3A%20none%3B%20-webkit-text-stroke-width%3A%200px%3B%20white-space%3A%20normal%3B%20word-spacing%3A%200px%3B%20margin%3A%200px%200px%2010px%200px%3B%22%3ELet%E2%80%99s%20follow%20the%20step%201%20in%20this%20%3CA%20style%3D%22background-color%3A%20transparent%3B%20box-sizing%3A%20border-box%3B%20color%3A%20%23337ab7%3B%20text-decoration%3A%20none%3B%22%20href%3D%22http%3A%2F%2Flearn.iis.net%2Fpage.aspx%2F488%2Fusing-failed-request-tracing-rules-to-troubleshoot-application-request-routing-arr%2Frev%2F10%22%20target%3D%22_blank%22%20rel%3D%22nofollow%20noopener%20noreferrer%20noopener%20noreferrer%22%3Earticle%3C%2FA%3E%20to%20create%20a%20FREB%20rule%20(create%20for%20HTTP%20400%20error%20message)%20on%20that%20website%2C%20or%20application.%20Below%20is%20how%20my%20web.config%20section%20with%20a%20FREB%20rule%20for%20400%20Error%20code%20(under%20%3CSYSTEM.WEBSERVER%3E%20section)%20look%20like%3A%3C%2FSYSTEM.WEBSERVER%3E%3C%2FP%3E%0A%3CBLOCKQUOTE%20style%3D%22border-left-color%3A%20%23eeeeee%3B%20border-left-style%3A%20solid%3B%20border-left-width%3A%205px%3B%20box-sizing%3A%20border-box%3B%20color%3A%20%23333333%3B%20font-family%3A%20%26amp%3Bquot%3B%20segoe%20ui%26amp%3Bquot%3B%2Ctahoma%2Carial%2C%26amp%3Bquot%3Bhelvetica%20neue%26amp%3Bquot%3B%2Chelvetica%2Csans-serif%3B%20font-size%3A%2017.5px%3B%20font-style%3A%20normal%3B%20font-variant%3A%20normal%3B%20font-weight%3A%20400%3B%20letter-spacing%3A%20normal%3B%20orphans%3A%202%3B%20text-align%3A%20left%3B%20text-decoration%3A%20none%3B%20text-indent%3A%200px%3B%20text-transform%3A%20none%3B%20-webkit-text-stroke-width%3A%200px%3B%20white-space%3A%20normal%3B%20word-spacing%3A%200px%3B%20padding%3A%2010px%2020px%2010px%2020px%3B%20margin%3A%200px%200px%2020px%200px%3B%22%3E%0A%3CPRE%20class%3D%22code%22%20style%3D%22background-color%3A%20%23f5f5f5%3B%20border-bottom-left-radius%3A%204px%3B%20border-bottom-right-radius%3A%204px%3B%20border-image-outset%3A%200%3B%20border-image-repeat%3A%20stretch%3B%20border-image-slice%3A%20100%25%3B%20border-image-source%3A%20none%3B%20border-image-width%3A%201%3B%20border-top-left-radius%3A%204px%3B%20border-top-right-radius%3A%204px%3B%20box-sizing%3A%20border-box%3B%20color%3A%20%23333333%3B%20display%3A%20block%3B%20font-family%3A%20Menlo%2CMonaco%2CConsolas%2C%26amp%3Bquot%3B%20courier%20new%26amp%3Bquot%3B%2Cmonospace%3B%20font-size%3A%2013px%3B%20height%3A%20226px%3B%20line-height%3A%201.4285%3B%20overflow%3A%20auto%3B%20overflow-wrap%3A%20break-word%3B%20width%3A%20865px%3B%20word-break%3A%20break-all%3B%20padding%3A%209.5px%3B%20margin%3A%200px%200px%2010px%200px%3B%20border%3A%201px%20solid%20%23cccccc%3B%22%3E%3CSPAN%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20blue%3B%22%3E%26lt%3B%3C%2FSPAN%3E%3CSPAN%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20%23a31515%3B%22%3Etracing%3C%2FSPAN%3E%3CSPAN%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20blue%3B%22%3E%26gt%3B%0A%20%20%26lt%3B%3C%2FSPAN%3E%3CSPAN%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20%23a31515%3B%22%3EtraceFailedRequests%3C%2FSPAN%3E%3CSPAN%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20blue%3B%22%3E%26gt%3B%0A%20%20%20%20%26lt%3B%3C%2FSPAN%3E%3CSPAN%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20%23a31515%3B%22%3Eremove%20%3C%2FSPAN%3E%3CSPAN%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20red%3B%22%3Epath%3C%2FSPAN%3E%3CSPAN%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20blue%3B%22%3E%3D%3C%2FSPAN%3E%22%3CSPAN%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20blue%3B%22%3E*%3C%2FSPAN%3E%22%20%3CSPAN%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20blue%3B%22%3E%2F%26gt%3B%0A%20%20%20%20%26lt%3B%3C%2FSPAN%3E%3CSPAN%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20%23a31515%3B%22%3Eadd%20%3C%2FSPAN%3E%3CSPAN%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20red%3B%22%3Epath%3C%2FSPAN%3E%3CSPAN%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20blue%3B%22%3E%3D%3C%2FSPAN%3E%22%3CSPAN%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20blue%3B%22%3E*%3C%2FSPAN%3E%22%3CSPAN%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20blue%3B%22%3E%26gt%3B%0A%20%20%20%20%20%20%26lt%3B%3C%2FSPAN%3E%3CSPAN%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20%23a31515%3B%22%3EtraceAreas%3C%2FSPAN%3E%3CSPAN%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20blue%3B%22%3E%26gt%3B%0A%20%20%20%20%20%20%20%20%26lt%3B%3C%2FSPAN%3E%3CSPAN%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20%23a31515%3B%22%3Eadd%20%3C%2FSPAN%3E%3CSPAN%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20red%3B%22%3Eprovider%3C%2FSPAN%3E%3CSPAN%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20blue%3B%22%3E%3D%3C%2FSPAN%3E%22%3CSPAN%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20blue%3B%22%3EASP%3C%2FSPAN%3E%22%20%3CSPAN%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20red%3B%22%3Everbosity%3C%2FSPAN%3E%3CSPAN%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20blue%3B%22%3E%3D%3C%2FSPAN%3E%22%3CSPAN%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20blue%3B%22%3EVerbose%3C%2FSPAN%3E%22%20%3CSPAN%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20blue%3B%22%3E%2F%26gt%3B%0A%20%20%20%20%20%20%20%20%26lt%3B%3C%2FSPAN%3E%3CSPAN%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20%23a31515%3B%22%3Eadd%20%3C%2FSPAN%3E%3CSPAN%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20red%3B%22%3Eprovider%3C%2FSPAN%3E%3CSPAN%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20blue%3B%22%3E%3D%3C%2FSPAN%3E%22%3CSPAN%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20blue%3B%22%3EASPNET%3C%2FSPAN%3E%22%20%3CSPAN%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20red%3B%22%3Eareas%3C%2FSPAN%3E%3CSPAN%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20blue%3B%22%3E%3D%3C%2FSPAN%3E%22%3CSPAN%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20blue%3B%22%3EInfrastructure%2CModule%2CPage%2CAppServices%3C%2FSPAN%3E%22%20%3CSPAN%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20red%3B%22%3Everbosity%3C%2FSPAN%3E%3CSPAN%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20blue%3B%22%3E%3D%3C%2FSPAN%3E%22%3CSPAN%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20blue%3B%22%3EVerbose%3C%2FSPAN%3E%22%20%3CSPAN%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20blue%3B%22%3E%2F%26gt%3B%0A%20%20%20%20%20%20%20%20%26lt%3B%3C%2FSPAN%3E%3CSPAN%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20%23a31515%3B%22%3Eadd%20%3C%2FSPAN%3E%3CSPAN%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20red%3B%22%3Eprovider%3C%2FSPAN%3E%3CSPAN%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20blue%3B%22%3E%3D%3C%2FSPAN%3E%22%3CSPAN%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20blue%3B%22%3EISAPI%20Extension%3C%2FSPAN%3E%22%20%3CSPAN%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20red%3B%22%3Everbosity%3C%2FSPAN%3E%3CSPAN%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20blue%3B%22%3E%3D%3C%2FSPAN%3E%22%3CSPAN%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20blue%3B%22%3EVerbose%3C%2FSPAN%3E%22%20%3CSPAN%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20blue%3B%22%3E%2F%26gt%3B%0A%20%20%20%20%20%20%20%20%26lt%3B%3C%2FSPAN%3E%3CSPAN%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20%23a31515%3B%22%3Eadd%20%3C%2FSPAN%3E%3CSPAN%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20red%3B%22%3Eprovider%3C%2FSPAN%3E%3CSPAN%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20blue%3B%22%3E%3D%3C%2FSPAN%3E%22%3CSPAN%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20blue%3B%22%3EWWW%20Server%3C%2FSPAN%3E%22%20%3CSPAN%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20red%3B%22%3Eareas%3C%2FSPAN%3E%3CSPAN%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20blue%3B%22%3E%3D%3C%2FSPAN%3E%22%3CSPAN%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20blue%3B%22%3EAuthentication%2CSecurity%2CFilter%2CStaticFile%2CCGI%2CCompression%2CCache%2CRequestNotifications%2CModule%2CRewrite%2CRequestRouting%3C%2FSPAN%3E%22%20%3CSPAN%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20red%3B%22%3Everbosity%3C%2FSPAN%3E%3CSPAN%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20blue%3B%22%3E%3D%3C%2FSPAN%3E%22%3CSPAN%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20blue%3B%22%3EVerbose%3C%2FSPAN%3E%22%20%3CSPAN%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20blue%3B%22%3E%2F%26gt%3B%0A%20%20%20%20%20%20%3CSPAN%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20%23a31515%3B%22%3EtraceAreas%3C%2FSPAN%3E%3CSPAN%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20blue%3B%22%3E%26gt%3B%0A%20%20%20%20%20%20%26lt%3B%3C%2FSPAN%3E%3CSPAN%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20%23a31515%3B%22%3EfailureDefinitions%20%3C%2FSPAN%3E%3CSPAN%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20red%3B%22%3EtimeTaken%3C%2FSPAN%3E%3CSPAN%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20blue%3B%22%3E%3D%3C%2FSPAN%3E%22%3CSPAN%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20blue%3B%22%3E00%3A00%3A00%3C%2FSPAN%3E%22%20%3CSPAN%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20red%3B%22%3EstatusCodes%3C%2FSPAN%3E%3CSPAN%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20blue%3B%22%3E%3D%3C%2FSPAN%3E%22%3CSPAN%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20blue%3B%22%3E400%3C%2FSPAN%3E%22%20%3CSPAN%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20blue%3B%22%3E%2F%26gt%3B%0A%20%20%20%20%3CSPAN%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20%23a31515%3B%22%3Eadd%3C%2FSPAN%3E%3CSPAN%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20blue%3B%22%3E%26gt%3B%0A%20%20%3CSPAN%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20%23a31515%3B%22%3EtraceFailedRequests%3C%2FSPAN%3E%3CSPAN%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20blue%3B%22%3E%26gt%3B%0A%3CSPAN%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20%23a31515%3B%22%3Etracing%3C%2FSPAN%3E%3CSPAN%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20blue%3B%22%3E%26gt%3B%3C%2FSPAN%3E%3C%2FSPAN%3E%3C%2FSPAN%3E%3C%2FSPAN%3E%3C%2FSPAN%3E%3C%2FPRE%3E%0A%3CP%20style%3D%22box-sizing%3A%20border-box%3B%20margin%3A%200px%3B%22%3E%26nbsp%3B%3C%2FP%3E%0A%3C%2FBLOCKQUOTE%3E%0A%3CP%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20%23333333%3B%20font-family%3A%20%26amp%3Bquot%3B%20segoe%20ui%26amp%3Bquot%3B%2Ctahoma%2Carial%2C%26amp%3Bquot%3Bhelvetica%20neue%26amp%3Bquot%3B%2Chelvetica%2Csans-serif%3B%20font-size%3A%2014px%3B%20font-style%3A%20normal%3B%20font-variant%3A%20normal%3B%20font-weight%3A%20400%3B%20letter-spacing%3A%20normal%3B%20orphans%3A%202%3B%20text-align%3A%20left%3B%20text-decoration%3A%20none%3B%20text-indent%3A%200px%3B%20text-transform%3A%20none%3B%20-webkit-text-stroke-width%3A%200px%3B%20white-space%3A%20normal%3B%20word-spacing%3A%200px%3B%20margin%3A%200px%200px%2010px%200px%3B%22%3ENow%2C%20let%20us%20try%20to%20browse%20the%20page%20which%20gives%20you%20the%20HTTP%20400%20error%20message.%20Unless%20you%20have%20turned%20the%20IIS%20HTTP%20error%20pages%20ON%2C%20you%20should%20see%20the%20complete%20error%20message%20when%20you%20browse%20the%20page%20from%20the%20server%20itself.%20By%20default%2C%20IIS%20HTTP%20error%20pages%20are%20set%20to%20%E2%80%9CDetailed%20errors%20for%20local%20requests%20and%20custom%20error%20pages%20for%20remote%20requests%E2%80%9D.%20In%20my%20example%2C%20since%20it%20is%20a%20local%20request%2C%20and%20we%20can%20see%20the%20complete%20error%20message.%3C%2FP%3E%0A%3CP%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20%23333333%3B%20font-family%3A%20%26amp%3Bquot%3B%20segoe%20ui%26amp%3Bquot%3B%2Ctahoma%2Carial%2C%26amp%3Bquot%3Bhelvetica%20neue%26amp%3Bquot%3B%2Chelvetica%2Csans-serif%3B%20font-size%3A%2014px%3B%20font-style%3A%20normal%3B%20font-variant%3A%20normal%3B%20font-weight%3A%20400%3B%20letter-spacing%3A%20normal%3B%20orphans%3A%202%3B%20text-align%3A%20left%3B%20text-decoration%3A%20none%3B%20text-indent%3A%200px%3B%20text-transform%3A%20none%3B%20-webkit-text-stroke-width%3A%200px%3B%20white-space%3A%20normal%3B%20word-spacing%3A%200px%3B%20margin%3A%200px%200px%2010px%200px%3B%22%3EAfter%20browsing%20the%20page%2C%20you%20should%20see%20the%20FREB%20log%20file%20created%20under%20the%20%25SystemDrive%25%5Cinetpub%5Clogs%5CFailedReqLogFiles%5CW3SVC%26lt%3B%23ID%26gt%3B%20folder.%20Below%20is%20how%20it%20looks%20after%20you%20open%20this.%20This%20is%20an%20XML%20file%2C%20and%20consumes%20a%20powerful%20freb.XSL%20located%20in%20the%20same%20folder.%3C%2FP%3E%0A%3CP%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20%23333333%3B%20font-family%3A%20%26amp%3Bquot%3B%20segoe%20ui%26amp%3Bquot%3B%2Ctahoma%2Carial%2C%26amp%3Bquot%3Bhelvetica%20neue%26amp%3Bquot%3B%2Chelvetica%2Csans-serif%3B%20font-size%3A%2014px%3B%20font-style%3A%20normal%3B%20font-variant%3A%20normal%3B%20font-weight%3A%20400%3B%20letter-spacing%3A%20normal%3B%20orphans%3A%202%3B%20text-align%3A%20left%3B%20text-decoration%3A%20none%3B%20text-indent%3A%200px%3B%20text-transform%3A%20none%3B%20-webkit-text-stroke-width%3A%200px%3B%20white-space%3A%20normal%3B%20word-spacing%3A%200px%3B%20margin%3A%200px%200px%2010px%200px%3B%22%3E%26nbsp%3B%3C%2FP%3E%0A%3CBLOCKQUOTE%20style%3D%22border-left-color%3A%20%23eeeeee%3B%20border-left-style%3A%20solid%3B%20border-left-width%3A%205px%3B%20box-sizing%3A%20border-box%3B%20color%3A%20%23333333%3B%20font-family%3A%20%26amp%3Bquot%3B%20segoe%20ui%26amp%3Bquot%3B%2Ctahoma%2Carial%2C%26amp%3Bquot%3Bhelvetica%20neue%26amp%3Bquot%3B%2Chelvetica%2Csans-serif%3B%20font-size%3A%2017.5px%3B%20font-style%3A%20normal%3B%20font-variant%3A%20normal%3B%20font-weight%3A%20400%3B%20letter-spacing%3A%20normal%3B%20orphans%3A%202%3B%20text-align%3A%20left%3B%20text-decoration%3A%20none%3B%20text-indent%3A%200px%3B%20text-transform%3A%20none%3B%20-webkit-text-stroke-width%3A%200px%3B%20white-space%3A%20normal%3B%20word-spacing%3A%200px%3B%20padding%3A%2010px%2020px%2010px%2020px%3B%20margin%3A%200px%200px%2020px%200px%3B%22%3E%0A%3CP%20style%3D%22box-sizing%3A%20border-box%3B%20margin%3A%200px%3B%22%3E%3CA%20style%3D%22background-color%3A%20transparent%3B%20box-sizing%3A%20border-box%3B%20color%3A%20%23337ab7%3B%20text-decoration%3A%20none%3B%22%20href%3D%22https%3A%2F%2Fmsdnshared.blob.core.windows.net%2Fmedia%2FTNBlogsFS%2FBlogFileStorage%2Fblogs_msdn%2Fwebtopics%2FWindowsLiveWriter%2FTroubleshootingusingFREBpart1_3129%2Fimage_6.png%22%20target%3D%22_blank%22%20rel%3D%22nofollow%20noopener%20noreferrer%20noopener%20noreferrer%22%3E%3CIMG%20width%3D%22480%22%20height%3D%22355%22%20title%3D%22image%22%20style%3D%22border-image-outset%3A%200%3B%20border-image-repeat%3A%20stretch%3B%20border-image-slice%3A%20100%25%3B%20border-image-source%3A%20none%3B%20border-image-width%3A%201%3B%20box-sizing%3A%20border-box%3B%20display%3A%20inline%3B%20height%3A%20auto%3B%20max-width%3A%20100%25%3B%20vertical-align%3A%20middle%3B%20border%3A%200px%20none%20currentColor%3B%22%20alt%3D%22image%22%20src%3D%22https%3A%2F%2Fmsdnshared.blob.core.windows.net%2Fmedia%2FTNBlogsFS%2FBlogFileStorage%2Fblogs_msdn%2Fwebtopics%2FWindowsLiveWriter%2FTroubleshootingusingFREBpart1_3129%2Fimage_thumb_2.png%22%20border%3D%220%22%20%2F%3E%3C%2FA%3E%3C%2FP%3E%0A%3C%2FBLOCKQUOTE%3E%0A%3CP%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20%23333333%3B%20font-family%3A%20%26amp%3Bquot%3B%20segoe%20ui%26amp%3Bquot%3B%2Ctahoma%2Carial%2C%26amp%3Bquot%3Bhelvetica%20neue%26amp%3Bquot%3B%2Chelvetica%2Csans-serif%3B%20font-size%3A%2014px%3B%20font-style%3A%20normal%3B%20font-variant%3A%20normal%3B%20font-weight%3A%20400%3B%20letter-spacing%3A%20normal%3B%20orphans%3A%202%3B%20text-align%3A%20left%3B%20text-decoration%3A%20none%3B%20text-indent%3A%200px%3B%20text-transform%3A%20none%3B%20-webkit-text-stroke-width%3A%200px%3B%20white-space%3A%20normal%3B%20word-spacing%3A%200px%3B%20margin%3A%200px%200px%2010px%200px%3B%22%3EI%E2%80%99ve%20highlighted%20the%20part%20of%20the%20file%20which%20you%20should%20look%20at%20first.%20Under%20%E2%80%9CErrors%20%26amp%3B%20Warnings%E2%80%9D%20you%20will%20see%20the%20information%20about%20the%20event%20which%20in%20fact%20set%20the%20status%20of%20the%20response%20to%20what%20this%20trace%20has%20been%20triggered%20on.%20The%20interesting%20thing%20to%20look%20for%20is%20the%20%E2%80%9CModule%20Name%E2%80%9D%20which%20has%20set%20the%20status.%20In%20this%20case%2C%20we%20see%20%E2%80%9CMyModule%E2%80%9D%20as%20the%20Module%20Name.%20If%20you%20click%20on%20that%20entry%2C%20you%20will%20see%20more%20information%20about%20that%20event%3A%3C%2FP%3E%0A%3CBLOCKQUOTE%20style%3D%22border-left-color%3A%20%23eeeeee%3B%20border-left-style%3A%20solid%3B%20border-left-width%3A%205px%3B%20box-sizing%3A%20border-box%3B%20color%3A%20%23333333%3B%20font-family%3A%20%26amp%3Bquot%3B%20segoe%20ui%26amp%3Bquot%3B%2Ctahoma%2Carial%2C%26amp%3Bquot%3Bhelvetica%20neue%26amp%3Bquot%3B%2Chelvetica%2Csans-serif%3B%20font-size%3A%2017.5px%3B%20font-style%3A%20normal%3B%20font-variant%3A%20normal%3B%20font-weight%3A%20400%3B%20letter-spacing%3A%20normal%3B%20orphans%3A%202%3B%20text-align%3A%20left%3B%20text-decoration%3A%20none%3B%20text-indent%3A%200px%3B%20text-transform%3A%20none%3B%20-webkit-text-stroke-width%3A%200px%3B%20white-space%3A%20normal%3B%20word-spacing%3A%200px%3B%20padding%3A%2010px%2020px%2010px%2020px%3B%20margin%3A%200px%200px%2020px%200px%3B%22%3E%0A%3CP%20style%3D%22box-sizing%3A%20border-box%3B%20margin%3A%200px%3B%22%3E%3CA%20style%3D%22background-color%3A%20transparent%3B%20box-sizing%3A%20border-box%3B%20color%3A%20%23337ab7%3B%20text-decoration%3A%20none%3B%22%20href%3D%22https%3A%2F%2Fmsdnshared.blob.core.windows.net%2Fmedia%2FTNBlogsFS%2FBlogFileStorage%2Fblogs_msdn%2Fwebtopics%2FWindowsLiveWriter%2FTroubleshootingusingFREBpart1_3129%2Fimage_8.png%22%20target%3D%22_blank%22%20rel%3D%22nofollow%20noopener%20noreferrer%20noopener%20noreferrer%22%3E%3CIMG%20width%3D%22477%22%20height%3D%22215%22%20title%3D%22image%22%20style%3D%22border-image-outset%3A%200%3B%20border-image-repeat%3A%20stretch%3B%20border-image-slice%3A%20100%25%3B%20border-image-source%3A%20none%3B%20border-image-width%3A%201%3B%20box-sizing%3A%20border-box%3B%20display%3A%20inline%3B%20height%3A%20auto%3B%20max-width%3A%20100%25%3B%20vertical-align%3A%20middle%3B%20border%3A%200px%20none%20currentColor%3B%22%20alt%3D%22image%22%20src%3D%22https%3A%2F%2Fmsdnshared.blob.core.windows.net%2Fmedia%2FTNBlogsFS%2FBlogFileStorage%2Fblogs_msdn%2Fwebtopics%2FWindowsLiveWriter%2FTroubleshootingusingFREBpart1_3129%2Fimage_thumb_3.png%22%20border%3D%220%22%20%2F%3E%3C%2FA%3E%3C%2FP%3E%0A%3C%2FBLOCKQUOTE%3E%0A%3CP%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20%23333333%3B%20font-family%3A%20%26amp%3Bquot%3B%20segoe%20ui%26amp%3Bquot%3B%2Ctahoma%2Carial%2C%26amp%3Bquot%3Bhelvetica%20neue%26amp%3Bquot%3B%2Chelvetica%2Csans-serif%3B%20font-size%3A%2014px%3B%20font-style%3A%20normal%3B%20font-variant%3A%20normal%3B%20font-weight%3A%20400%3B%20letter-spacing%3A%20normal%3B%20orphans%3A%202%3B%20text-align%3A%20left%3B%20text-decoration%3A%20none%3B%20text-indent%3A%200px%3B%20text-transform%3A%20none%3B%20-webkit-text-stroke-width%3A%200px%3B%20white-space%3A%20normal%3B%20word-spacing%3A%200px%3B%20margin%3A%200px%200px%2010px%200px%3B%22%3EClick%20on%20the%20%E2%80%9CCompact%20View%E2%80%9D%20at%20the%20top%2C%20and%20you%20will%20find%20all%20the%20events%20which%20arose%20during%20the%20lifetime%20of%20that%20particular%20request.%3C%2FP%3E%0A%3CBLOCKQUOTE%20style%3D%22border-left-color%3A%20%23eeeeee%3B%20border-left-style%3A%20solid%3B%20border-left-width%3A%205px%3B%20box-sizing%3A%20border-box%3B%20color%3A%20%23333333%3B%20font-family%3A%20%26amp%3Bquot%3B%20segoe%20ui%26amp%3Bquot%3B%2Ctahoma%2Carial%2C%26amp%3Bquot%3Bhelvetica%20neue%26amp%3Bquot%3B%2Chelvetica%2Csans-serif%3B%20font-size%3A%2017.5px%3B%20font-style%3A%20normal%3B%20font-variant%3A%20normal%3B%20font-weight%3A%20400%3B%20letter-spacing%3A%20normal%3B%20orphans%3A%202%3B%20text-align%3A%20left%3B%20text-decoration%3A%20none%3B%20text-indent%3A%200px%3B%20text-transform%3A%20none%3B%20-webkit-text-stroke-width%3A%200px%3B%20white-space%3A%20normal%3B%20word-spacing%3A%200px%3B%20padding%3A%2010px%2020px%2010px%2020px%3B%20margin%3A%200px%200px%2020px%200px%3B%22%3E%0A%3CP%20style%3D%22box-sizing%3A%20border-box%3B%20margin%3A%200px%3B%22%3E%3CA%20style%3D%22background-color%3A%20transparent%3B%20box-sizing%3A%20border-box%3B%20color%3A%20%23337ab7%3B%20text-decoration%3A%20none%3B%22%20href%3D%22https%3A%2F%2Fmsdnshared.blob.core.windows.net%2Fmedia%2FTNBlogsFS%2FBlogFileStorage%2Fblogs_msdn%2Fwebtopics%2FWindowsLiveWriter%2FTroubleshootingusingFREBpart1_3129%2Fimage_10.png%22%20target%3D%22_blank%22%20rel%3D%22nofollow%20noopener%20noreferrer%20noopener%20noreferrer%22%3E%3CIMG%20width%3D%22783%22%20height%3D%22183%22%20title%3D%22image%22%20style%3D%22border-image-outset%3A%200%3B%20border-image-repeat%3A%20stretch%3B%20border-image-slice%3A%20100%25%3B%20border-image-source%3A%20none%3B%20border-image-width%3A%201%3B%20box-sizing%3A%20border-box%3B%20display%3A%20inline%3B%20height%3A%20auto%3B%20max-width%3A%20100%25%3B%20vertical-align%3A%20middle%3B%20border%3A%200px%20none%20currentColor%3B%22%20alt%3D%22image%22%20src%3D%22https%3A%2F%2Fmsdnshared.blob.core.windows.net%2Fmedia%2FTNBlogsFS%2FBlogFileStorage%2Fblogs_msdn%2Fwebtopics%2FWindowsLiveWriter%2FTroubleshootingusingFREBpart1_3129%2Fimage_thumb_4.png%22%20border%3D%220%22%20%2F%3E%3C%2FA%3E%3C%2FP%3E%0A%3C%2FBLOCKQUOTE%3E%0A%3CP%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20%23333333%3B%20font-family%3A%20%26amp%3Bquot%3B%20segoe%20ui%26amp%3Bquot%3B%2Ctahoma%2Carial%2C%26amp%3Bquot%3Bhelvetica%20neue%26amp%3Bquot%3B%2Chelvetica%2Csans-serif%3B%20font-size%3A%2014px%3B%20font-style%3A%20normal%3B%20font-variant%3A%20normal%3B%20font-weight%3A%20400%3B%20letter-spacing%3A%20normal%3B%20orphans%3A%202%3B%20text-align%3A%20left%3B%20text-decoration%3A%20none%3B%20text-indent%3A%200px%3B%20text-transform%3A%20none%3B%20-webkit-text-stroke-width%3A%200px%3B%20white-space%3A%20normal%3B%20word-spacing%3A%200px%3B%20margin%3A%200px%200px%2010px%200px%3B%22%3EAs%20you%20see%2C%20this%20module%20has%20registered%20for%20the%20RELEASE_REQUEST_STATE%20notification%2C%20and%20it%20does%20set%20the%20Response%20status%20to%20400%20in%20its%20handler%20for%20that%20notification%20(In%20ASP.NET%2C%20it%20is%20context.ReleaseRequestState%20Event%20Handler).%3C%2FP%3E%0A%3CP%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20%23333333%3B%20font-family%3A%20%26amp%3Bquot%3B%20segoe%20ui%26amp%3Bquot%3B%2Ctahoma%2Carial%2C%26amp%3Bquot%3Bhelvetica%20neue%26amp%3Bquot%3B%2Chelvetica%2Csans-serif%3B%20font-size%3A%2014px%3B%20font-style%3A%20normal%3B%20font-variant%3A%20normal%3B%20font-weight%3A%20400%3B%20letter-spacing%3A%20normal%3B%20orphans%3A%202%3B%20text-align%3A%20left%3B%20text-decoration%3A%20none%3B%20text-indent%3A%200px%3B%20text-transform%3A%20none%3B%20-webkit-text-stroke-width%3A%200px%3B%20white-space%3A%20normal%3B%20word-spacing%3A%200px%3B%20margin%3A%200px%200px%2010px%200px%3B%22%3ESo%2C%20now%20we%20know%20that%20this%20HTTP%20400%20is%20set%20by%20a%20managed%20module%20called%20%E2%80%9CMyModule%E2%80%9D%20and%20its%20class%20name%20is%20%E2%80%9CMyBadModule%E2%80%9D%20(see%20the%20trace%20entry%20%23176).%20Now%2C%20you%20can%20go%20ahead%20and%20try%20debugging%20that%20module.%20In%20the%20future%20blog%20posts%2C%20I%20will%20try%20to%20cover%20some%20more%20troubleshooting%20scenarios%20using%20FREB.%3C%2FP%3E%0A%3CP%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20%23333333%3B%20font-family%3A%20%26amp%3Bquot%3B%20segoe%20ui%26amp%3Bquot%3B%2Ctahoma%2Carial%2C%26amp%3Bquot%3Bhelvetica%20neue%26amp%3Bquot%3B%2Chelvetica%2Csans-serif%3B%20font-size%3A%2014px%3B%20font-style%3A%20normal%3B%20font-variant%3A%20normal%3B%20font-weight%3A%20400%3B%20letter-spacing%3A%20normal%3B%20orphans%3A%202%3B%20text-align%3A%20left%3B%20text-decoration%3A%20none%3B%20text-indent%3A%200px%3B%20text-transform%3A%20none%3B%20-webkit-text-stroke-width%3A%200px%3B%20white-space%3A%20normal%3B%20word-spacing%3A%200px%3B%20margin%3A%200px%200px%2010px%200px%3B%22%3EHappy%20FREBing!%3C%2FP%3E%0A%3CP%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20%23333333%3B%20font-family%3A%20%26amp%3Bquot%3B%20segoe%20ui%26amp%3Bquot%3B%2Ctahoma%2Carial%2C%26amp%3Bquot%3Bhelvetica%20neue%26amp%3Bquot%3B%2Chelvetica%2Csans-serif%3B%20font-size%3A%2014px%3B%20font-style%3A%20normal%3B%20font-variant%3A%20normal%3B%20font-weight%3A%20400%3B%20letter-spacing%3A%20normal%3B%20orphans%3A%202%3B%20text-align%3A%20left%3B%20text-decoration%3A%20none%3B%20text-indent%3A%200px%3B%20text-transform%3A%20none%3B%20-webkit-text-stroke-width%3A%200px%3B%20white-space%3A%20normal%3B%20word-spacing%3A%200px%3B%20margin%3A%200px%200px%2010px%200px%3B%22%3E%3CSTRONG%3EAuthor%3A%20Rakki%20Muthukumar%3C%2FSTRONG%3E%3C%2FP%3E%3C%2FLINGO-BODY%3E

FREB (Failed Requests Tracing – formerly known as Failed Request Event Buffering) is one of the nicest features released with IIS7 which would come in handy during troubleshooting. It does request based tracing, and produces a log file (in .xml format) that shows events and notifications from the various modules that worked on the request during its lifecycle.

This is going to be a series of posts talking about using FREB during troubleshooting various scenarios. In this blog post, I’m going to cover few scenarios like troubleshooting a specific error message, and what to look for in the FREB output.

Troubleshooting a simple error code

First, let’s take an example of troubleshooting a simple straight forward error code – HTTP 400 Bad Request. Whenever you get HTTP 400 Bad Request, the first thing to check is to find out where the HTTP 400 is logged – is it in IIS W3SVC logs, or in the HTTPERR logs. In this example, it would be in the W3SVC log, and that tells us that the request is actually processed by the IIS pipeline, and returned with HTTP 400 to the client. Only if the 400 is in IIS logs, we would be able to use FREB for the troubleshooting. Below is the sample screenshot of the error message (when browsed from the server itself – using localhost):

image

Let’s follow the step 1 in this article to create a FREB rule (create for HTTP 400 error message) on that website, or application. Below is how my web.config section with a FREB rule for 400 Error code (under <system.webServer> section) look like:

<tracing>
  <traceFailedRequests>
    <remove path="*" />
    <add path="*">
      <traceAreas>
        <add provider="ASP" verbosity="Verbose" />
        <add provider="ASPNET" areas="Infrastructure,Module,Page,AppServices" verbosity="Verbose" />
        <add provider="ISAPI Extension" verbosity="Verbose" />
        <add provider="WWW Server" areas="Authentication,Security,Filter,StaticFile,CGI,Compression,Cache,RequestNotifications,Module,Rewrite,RequestRouting" verbosity="Verbose" />
      </traceAreas>
      <failureDefinitions timeTaken="00:00:00" statusCodes="400" />
    </add>
  </traceFailedRequests>
</tracing>

 

Now, let us try to browse the page which gives you the HTTP 400 error message. Unless you have turned the IIS HTTP error pages ON, you should see the complete error message when you browse the page from the server itself. By default, IIS HTTP error pages are set to “Detailed errors for local requests and custom error pages for remote requests”. In my example, since it is a local request, and we can see the complete error message.

After browsing the page, you should see the FREB log file created under the %SystemDrive%\inetpub\logs\FailedReqLogFiles\W3SVC<#ID> folder. Below is how it looks after you open this. This is an XML file, and consumes a powerful freb.XSL located in the same folder.

 

image

I’ve highlighted the part of the file which you should look at first. Under “Errors & Warnings” you will see the information about the event which in fact set the status of the response to what this trace has been triggered on. The interesting thing to look for is the “Module Name” which has set the status. In this case, we see “MyModule” as the Module Name. If you click on that entry, you will see more information about that event:

image

Click on the “Compact View” at the top, and you will find all the events which arose during the lifetime of that particular request.

image

As you see, this module has registered for the RELEASE_REQUEST_STATE notification, and it does set the Response status to 400 in its handler for that notification (In ASP.NET, it is context.ReleaseRequestState Event Handler).

So, now we know that this HTTP 400 is set by a managed module called “MyModule” and its class name is “MyBadModule” (see the trace entry #176). Now, you can go ahead and try debugging that module. In the future blog posts, I will try to cover some more troubleshooting scenarios using FREB.

Happy FREBing!

Author: Rakki Muthukumar