Sometimes web browsers will only show you a generic error that could mean absolutely anything. If you enable IIS logs and look at those you may find out what the issue is if the problem is with the IIS server – but if the problem is in the application code this won’t show in IIS logs.
There are two steps to getting the error information you need.
1. In Internet Explorer you need to disable Friendly HTTP Errors. Press <Windows>+R and type inetcpl.cpl > Advanced > Untick “Show friendly HTTP error messages”.
If you are not the website administrator this is as far as you can go.
2. Back up your web sites web.config file.
3. Open up the website’s web.config file. Find the <system.web> tag and within this find <customErrors.
Remove this whole tag and replace it with:
Remember to click ‘Save’.