Are you getting into a scenario wherein randomly your Website loses or changes the SSL certificate bindings from within the IIS manager? And you realize it only when users complain that they are unable to reach the HTTPS site, or that they get a certificate warning. They are able to access the website over HTTP but not over HTTPS because the certificate binding is lost for the website, or they may be prompted that the certificate is expired, or the site name is incorrect. At this point of time you also notice that System Event log entry shows the following:
The above property is used to store a SSL certificate hash. It is specifically the ID 5506 entry you need to check for. That ID is the legacy property for certificate hash. Whenever any application/service which depends upon the ABO mapper runs/starts, it tries to initialize the ABO tree structure which includes generating custom nodes and properties. During this process it reads from this custom metadata section and tries to map the properties in the ABO tree structure. During mapping it deletes the current SSL mapping(s) at the http.sys level and recreates a new one using the above hash value. If this value is invalid for some reason it fails to add the new entry for SSL binding at the http.sys level. So in such a case the above registry key does not have an entry for the website’s IP:Port combination corresponding to the SSL setting in the UI like below:
Call stack output
If you use the Debugging Tools for Windows and the Microsoft symbol server to attach to the process Inetinfo.exe, you will notice a call stack that resembles the following below:
and then launching any application which requires ABO Mapper, for e.g. launching Inetmgr6.exe or enumerating using ADSUTIL VBscript.
This property is a legacy feature from IIS 6 days and ported onto IIS 7+. If we have correctly added the certificate in the IIS manager this specific property with id 5506 is not needed. Search for the above entry in your ApplicationHost.config file and remove the property in case you are seeing the above issue.
PS: I have got the above issue/resolution recently documented as a fast-publish KB article 2025598.