Home
%3CLINGO-SUB%20id%3D%22lingo-sub-326881%22%20slang%3D%22en-US%22%3ECannot%20perform%20CAS%20Asserts%20error%3C%2FLINGO-SUB%3E%3CLINGO-BODY%20id%3D%22lingo-body-326881%22%20slang%3D%22en-US%22%3E%3CP%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20%23333333%3B%20font-family%3A%20inherit%3B%20font-size%3A%2016px%3B%20font-style%3A%20normal%3B%20font-variant%3A%20normal%3B%20font-weight%3A%20300%3B%20letter-spacing%3A%20normal%3B%20line-height%3A%201.7142%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%3B%22%3E%E2%80%9CCannot%20perform%20CAS%20Asserts%E2%80%9D%20error%20may%20appear%20when%20you%20try%20to%20use%20a%20third-party%20library%20in%20a%20.NET%20application.%20This%20issue%20is%20related%20to%20the%20security%20implementation%20that%20protects%20your%20system%20from%20untrusted%20components.%3C%2FP%3E%0A%3CP%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20%23333333%3B%20font-family%3A%20inherit%3B%20font-size%3A%2016px%3B%20font-style%3A%20normal%3B%20font-variant%3A%20normal%3B%20font-weight%3A%20300%3B%20letter-spacing%3A%20normal%3B%20line-height%3A%201.7142%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%3B%22%3E%26nbsp%3B%3C%2FP%3E%0A%3CP%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20%23333333%3B%20font-family%3A%20inherit%3B%20font-size%3A%2016px%3B%20font-style%3A%20normal%3B%20font-variant%3A%20normal%3B%20font-weight%3A%20300%3B%20letter-spacing%3A%20normal%3B%20line-height%3A%201.7142%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%3B%22%3EThe%20error%20message%3A%3C%2FP%3E%0A%3CPRE%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%233e3e3e%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%20font-style%3A%20normal%3B%20font-variant%3A%20normal%3B%20font-weight%3A%20300%3B%20letter-spacing%3A%20normal%3B%20line-height%3A%201.7142%3B%20orphans%3A%202%3B%20overflow%3A%20auto%3B%20overflow-wrap%3A%20break-word%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%20pre%3B%20word-break%3A%20break-all%3B%20word-spacing%3A%200px%3B%20padding%3A%2011.5px%3B%20margin%3A%200px%200px%2012px%200px%3B%20border%3A%201px%20solid%20%23cccccc%3B%22%3ESystem.InvalidOperationException%3A%20Cannot%20perform%20CAS%20Asserts%20in%20Security%20Transparent%20methods%3C%2FPRE%3E%0A%3CH2%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20inherit%3B%20font-family%3A%20inherit%3B%20font-size%3A%2024px%3B%20font-style%3A%20normal%3B%20font-variant%3A%20normal%3B%20font-weight%3A%20normal%3B%20letter-spacing%3A%20normal%3B%20line-height%3A%201.2%3B%20margin-bottom%3A%2012px%3B%20margin-top%3A%2024px%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%22%20id%3D%22toc-hId-1764706248%22%20id%3D%22toc-hId-1766523627%22%3ECAS%20(Code%20Access%20Security)%3C%2FH2%3E%0A%3CP%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20%23333333%3B%20font-family%3A%20inherit%3B%20font-size%3A%2016px%3B%20font-style%3A%20normal%3B%20font-variant%3A%20normal%3B%20font-weight%3A%20300%3B%20letter-spacing%3A%20normal%3B%20line-height%3A%201.7142%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%3B%22%3ECAS%20is%20a%20security%20implementation%20included%20in%20.NET%20Framework%20to%20secure%20the%20system%20against%20malicious%20code%20and%20components.%3C%2FP%3E%0A%3CP%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20%23333333%3B%20font-family%3A%20inherit%3B%20font-size%3A%2016px%3B%20font-style%3A%20normal%3B%20font-variant%3A%20normal%3B%20font-weight%3A%20300%3B%20letter-spacing%3A%20normal%3B%20line-height%3A%201.7142%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%3B%22%3E%26nbsp%3B%3C%2FP%3E%0A%3CBLOCKQUOTE%20style%3D%22border-left-color%3A%20%23e8e8e8%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%20segoeui%26amp%3Bquot%3B%2C%26amp%3Bquot%3Blato%26amp%3Bquot%3B%2C%26amp%3Bquot%3Bhelvetica%20neue%26amp%3Bquot%3B%2Chelvetica%2Carial%2Csans-serif%3B%20font-size%3A%2014px%3B%20font-style%3A%20normal%3B%20font-variant%3A%20normal%3B%20font-weight%3A%20300%3B%20letter-spacing%3A%20normal%3B%20line-height%3A%201.7142%3B%20opacity%3A%200.8%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%200px%2024px%200px%2024px%3B%20margin%3A%200px%200px%2024px%200px%3B%22%3E%0A%3CP%20style%3D%22box-sizing%3A%20border-box%3B%20font-family%3A%20inherit%3B%20font-size%3A%2016px%3B%20font-weight%3A%20300%3B%20line-height%3A%201.7142%3B%20margin%3A%200px%3B%22%3EThe%20.NET%20Framework%20provides%20a%20mechanism%20for%20the%20enforcement%20of%20varying%20levels%20of%20trust%20on%20different%20code%20running%20in%20the%20same%20application%20called%20Code%20Access%20Security%20(CAS).%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%20inherit%3B%20font-size%3A%2016px%3B%20font-style%3A%20normal%3B%20font-variant%3A%20normal%3B%20font-weight%3A%20300%3B%20letter-spacing%3A%20normal%3B%20line-height%3A%201.7142%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%3B%22%3E%3CA%20style%3D%22background-color%3A%20transparent%3B%20box-sizing%3A%20border-box%3B%20color%3A%20%23146cac%3B%20text-decoration%3A%20underline%3B%22%20href%3D%22https%3A%2F%2Fnam06.safelinks.protection.outlook.com%2F%3Furl%3Dhttps%253A%252F%252Fdocs.microsoft.com%252Fen-us%252Fdotnet%252Fframework%252Fmisc%252Fcode-access-security%26amp%3Bdata%3D02%257C01%257CNedim.Sahin%2540microsoft.com%257C45496a89e07c490e543e08d685650167%257C72f988bf86f141af91ab2d7cd011db47%257C1%257C0%257C636843066190763459%26amp%3Bsdata%3Dd59jx4Q0dd3IptEIIUGsKbvTKmkDANcKzgVH3MwMoXQ%253D%26amp%3Breserved%3D0%22%20target%3D%22_blank%22%20rel%3D%22nofollow%20noopener%20noreferrer%20noopener%20noreferrer%22%3EMicrosott%20Docs%3C%2FA%3E%3C%2FP%3E%0A%3CP%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20%23333333%3B%20font-family%3A%20inherit%3B%20font-size%3A%2016px%3B%20font-style%3A%20normal%3B%20font-variant%3A%20normal%3B%20font-weight%3A%20300%3B%20letter-spacing%3A%20normal%3B%20line-height%3A%201.7142%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%3B%22%3E%26nbsp%3B%3C%2FP%3E%0A%3CH2%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20inherit%3B%20font-family%3A%20inherit%3B%20font-size%3A%2024px%3B%20font-style%3A%20normal%3B%20font-variant%3A%20normal%3B%20font-weight%3A%20normal%3B%20letter-spacing%3A%20normal%3B%20line-height%3A%201.2%3B%20margin-bottom%3A%2012px%3B%20margin-top%3A%2024px%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%22%20id%3D%22toc-hId--787450713%22%20id%3D%22toc-hId--785633334%22%3ERoot%20Cause%3C%2FH2%3E%0A%3CP%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20%23333333%3B%20font-family%3A%20inherit%3B%20font-size%3A%2016px%3B%20font-style%3A%20normal%3B%20font-variant%3A%20normal%3B%20font-weight%3A%20300%3B%20letter-spacing%3A%20normal%3B%20line-height%3A%201.7142%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%3B%22%3EThe%20application%20is%20probably%20trying%20to%20use%20an%20external%20library%20which%20is%20not%20trusted%20by%20CAS.%20You%20might%20have%20upgraded%20.NET%20Framework%20version%20in%20the%20development%20machine.%20If%20this%20is%20the%20case%2C%20update%20your%20code%20as%20per%20the%20new%20CAS%20requirements%20that%20are%20introduced%20with%20the%20new%20.NET%20Framework.%3C%2FP%3E%0A%3CP%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20%23333333%3B%20font-family%3A%20inherit%3B%20font-size%3A%2016px%3B%20font-style%3A%20normal%3B%20font-variant%3A%20normal%3B%20font-weight%3A%20300%3B%20letter-spacing%3A%20normal%3B%20line-height%3A%201.7142%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%3B%22%3EMore%20information%20about%20major%20CAS%20changes%20in%20.NET%20Framework%204.0%3A%20%3CA%20style%3D%22background-color%3A%20transparent%3B%20box-sizing%3A%20border-box%3B%20color%3A%20%23146cac%3B%20text-decoration%3A%20underline%3B%22%20href%3D%22https%3A%2F%2Fnam06.safelinks.protection.outlook.com%2F%3Furl%3Dhttps%253A%252F%252Fdocs.microsoft.com%252Fen-us%252Fdotnet%252Fframework%252Fmisc%252Fsecurity-transparent-code-level-2%26amp%3Bdata%3D02%257C01%257CNedim.Sahin%2540microsoft.com%257C45496a89e07c490e543e08d685650167%257C72f988bf86f141af91ab2d7cd011db47%257C1%257C0%257C636843066190773445%26amp%3Bsdata%3Djq1issvfCnxB9TJkPlFZK9ywNz2AwTyRVm3Uyvd9m5U%253D%26amp%3Breserved%3D0%22%20target%3D%22_blank%22%20rel%3D%22nofollow%20noopener%20noreferrer%20noopener%20noreferrer%22%3ELink%3C%2FA%3E%3C%2FP%3E%0A%3CH2%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20inherit%3B%20font-family%3A%20inherit%3B%20font-size%3A%2024px%3B%20font-style%3A%20normal%3B%20font-variant%3A%20normal%3B%20font-weight%3A%20normal%3B%20letter-spacing%3A%20normal%3B%20line-height%3A%201.2%3B%20margin-bottom%3A%2012px%3B%20margin-top%3A%2024px%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%22%20id%3D%22toc-hId-955359622%22%20id%3D%22toc-hId-957177001%22%3ESolution%3C%2FH2%3E%0A%3CH4%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20inherit%3B%20font-family%3A%20inherit%3B%20font-size%3A%2018px%3B%20font-style%3A%20normal%3B%20font-variant%3A%20normal%3B%20font-weight%3A%20normal%3B%20letter-spacing%3A%20normal%3B%20line-height%3A%201.2%3B%20margin-bottom%3A%2012px%3B%20margin-top%3A%2012px%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%22%20id%3D%22toc-hId--1989824349%22%20id%3D%22toc-hId--1988006970%22%3ESolution%201%3A%20Full-trust%3C%2FH4%3E%0A%3CP%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20%23333333%3B%20font-family%3A%20inherit%3B%20font-size%3A%2016px%3B%20font-style%3A%20normal%3B%20font-variant%3A%20normal%3B%20font-weight%3A%20300%3B%20letter-spacing%3A%20normal%3B%20line-height%3A%201.7142%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%3B%22%3EMake%20your%20application%20a%20%E2%80%9Cfull-trust%E2%80%9D%20application%20unless%20the%20application%20is%20marked%20as%20security-transparent.%3C%2FP%3E%0A%3CH4%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20inherit%3B%20font-family%3A%20inherit%3B%20font-size%3A%2018px%3B%20font-style%3A%20normal%3B%20font-variant%3A%20normal%3B%20font-weight%3A%20normal%3B%20letter-spacing%3A%20normal%3B%20line-height%3A%201.2%3B%20margin-bottom%3A%2012px%3B%20margin-top%3A%2012px%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%22%20id%3D%22toc-hId--247014014%22%20id%3D%22toc-hId--245196635%22%3ESolution%202%3A%20GAC%3C%2FH4%3E%0A%3CP%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20%23333333%3B%20font-family%3A%20inherit%3B%20font-size%3A%2016px%3B%20font-style%3A%20normal%3B%20font-variant%3A%20normal%3B%20font-weight%3A%20300%3B%20letter-spacing%3A%20normal%3B%20line-height%3A%201.7142%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%3B%22%3EAdd%20the%20external%20DLLs%20into%20GAC%20(Global%20Assembly%20Cache)%20by%20using%20%3CA%20style%3D%22background-color%3A%20transparent%3B%20box-sizing%3A%20border-box%3B%20color%3A%20%23146cac%3B%20text-decoration%3A%20underline%3B%22%20href%3D%22https%3A%2F%2Fnam06.safelinks.protection.outlook.com%2F%3Furl%3Dhttps%253A%252F%252Fdocs.microsoft.com%252Fen-us%252Fdotnet%252Fframework%252Ftools%252Fgacutil-exe-gac-tool%26amp%3Bdata%3D02%257C01%257CNedim.Sahin%2540microsoft.com%257C45496a89e07c490e543e08d685650167%257C72f988bf86f141af91ab2d7cd011db47%257C1%257C0%257C636843066190773445%26amp%3Bsdata%3DiX5aWnHeOF0OG9zsIXW%252FY1vYoAyUNLTE60Xv9yaHJiA%253D%26amp%3Breserved%3D0%22%20target%3D%22_blank%22%20rel%3D%22nofollow%20noopener%20noreferrer%20noopener%20noreferrer%22%3EGacutil.exe%3C%2FA%3E.%20%3CA%20style%3D%22background-color%3A%20transparent%3B%20box-sizing%3A%20border-box%3B%20color%3A%20%23146cac%3B%20text-decoration%3A%20underline%3B%22%20href%3D%22https%3A%2F%2Fnam06.safelinks.protection.outlook.com%2F%3Furl%3Dhttps%253A%252F%252Fdocs.microsoft.com%252Fen-us%252Fdotnet%252Fframework%252Fapp-domains%252Fhow-to-install-an-assembly-into-the-gac%26amp%3Bdata%3D02%257C01%257CNedim.Sahin%2540microsoft.com%257C45496a89e07c490e543e08d685650167%257C72f988bf86f141af91ab2d7cd011db47%257C1%257C0%257C636843066190783438%26amp%3Bsdata%3D4M9IBu4kqdrqgxLpBZpxeDyoejDaqP9gB0LdapDUGF4%253D%26amp%3Breserved%3D0%22%20target%3D%22_blank%22%20rel%3D%22nofollow%20noopener%20noreferrer%20noopener%20noreferrer%22%3EThis%20article%3C%2FA%3E%20explains%20steps%20to%20install%20an%20assembly%20into%20GAC.%20Gacutil.exe%20comes%20with%20Windows%20SDK%20and%20Visual%20Studio.%3C%2FP%3E%0A%3CH4%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20inherit%3B%20font-family%3A%20inherit%3B%20font-size%3A%2018px%3B%20font-style%3A%20normal%3B%20font-variant%3A%20normal%3B%20font-weight%3A%20normal%3B%20letter-spacing%3A%20normal%3B%20line-height%3A%201.2%3B%20margin-bottom%3A%2012px%3B%20margin-top%3A%2012px%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%22%20id%3D%22toc-hId-1495796321%22%20id%3D%22toc-hId-1497613700%22%3ESolution%203%3A%20Code%20changes%3C%2FH4%3E%0A%3CP%20style%3D%22box-sizing%3A%20border-box%3B%20color%3A%20%23333333%3B%20font-family%3A%20inherit%3B%20font-size%3A%2016px%3B%20font-style%3A%20normal%3B%20font-variant%3A%20normal%3B%20font-weight%3A%20300%3B%20letter-spacing%3A%20normal%3B%20line-height%3A%201.7142%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%3B%22%3EChange%20your%20application%E2%80%99s%20code%20to%20make%20it%20compatible%20with%20the%20new%20CAS%20implementations.%20This%20is%20the%20best%20solution%20in%20the%20long-term.%20Refer%20to%20%3CA%20style%3D%22background-color%3A%20transparent%3B%20box-sizing%3A%20border-box%3B%20color%3A%20%23146cac%3B%20text-decoration%3A%20underline%3B%22%20href%3D%22https%3A%2F%2Fnam06.safelinks.protection.outlook.com%2F%3Furl%3Dhttps%253A%252F%252Fdocs.microsoft.com%252Fen-us%252Fdotnet%252Fframework%252Fmisc%252Fcode-access-security-basics%26amp%3Bdata%3D02%257C01%257CNedim.Sahin%2540microsoft.com%257C45496a89e07c490e543e08d685650167%257C72f988bf86f141af91ab2d7cd011db47%257C1%257C0%257C636843066190783438%26amp%3Bsdata%3DiGH3Bgj7oI8CLUiToGkRWemz0Or34LUPZGvBcnLX%252FdM%253D%26amp%3Breserved%3D0%22%20target%3D%22_blank%22%20rel%3D%22nofollow%20noopener%20noreferrer%20noopener%20noreferrer%22%3Ethis%3C%2FA%3E%20article%20for%20guidance.%3C%2FP%3E%3C%2FLINGO-BODY%3E
Microsoft

“Cannot perform CAS Asserts” error may appear when you try to use a third-party library in a .NET application. This issue is related to the security implementation that protects your system from untrusted components.

 

The error message:

System.InvalidOperationException: Cannot perform CAS Asserts in Security Transparent methods

CAS (Code Access Security)

CAS is a security implementation included in .NET Framework to secure the system against malicious code and components.

 

The .NET Framework provides a mechanism for the enforcement of varying levels of trust on different code running in the same application called Code Access Security (CAS).

Microsott Docs

 

Root Cause

The application is probably trying to use an external library which is not trusted by CAS. You might have upgraded .NET Framework version in the development machine. If this is the case, update your code as per the new CAS requirements that are introduced with the new .NET Framework.

More information about major CAS changes in .NET Framework 4.0: Link

Solution

Solution 1: Full-trust

Make your application a “full-trust” application unless the application is marked as security-transparent.

Solution 2: GAC

Add the external DLLs into GAC (Global Assembly Cache) by using Gacutil.exe. This article explains steps to install an assembly into GAC. Gacutil.exe comes with Windows SDK and Visual Studio.

Solution 3: Code changes

Change your application’s code to make it compatible with the new CAS implementations. This is the best solution in the long-term. Refer to this article for guidance.