You get “HTTP Error 500 - Internal server error” while browsing any file under a website or virtual directory whose home directory is a UNC. You will also see in IIS logs, the sc-status sc-substatus sc-win32-status as 500 16 1326.
Unknown user name or password configured for the UNC in IIS Metabase.
This “HTTP Error 500 - Internal server error” error occurs only when you have the website or the virtual directory configured for an UNC and it uses specific user name and password to connect to the UNC (not the logon user credentials).
Give correct username and password for connecting the UNC share on the IIS Manager -> Website or Virtual Directory properties -> Home Directory or Virtual Directory -> Connect As -> Network Directory Security Credentials window. Alternatively you can also set UNCUserName and UNCPassword properties on IIS Metabase for the website or the virtual directory when you have this problem.
User challenged for user credentials for every 5 minutes of inactivity while editing the site using FrontPage.
Website configured for Digest Authentication
It is a default behavior of the Digest Authentication to challenge the user for user credentials for every 300 seconds (5 minutes) of inactivity. However, there is a registry key which can be set to change the timeout period.
The above article also mentions that there is a registry entry DigestContextCacheTTL which may help to increase or decrease the time limit
Setting the following registry key may allow the user to change the timeout period:
Registry Path: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\InetInfo\Parameters
Data Type: REG_DWORD
Default Value: 300 (seconds)
Range: 0 - 4,294,967
When using Advanced Digest Authentication, this value overrides the Time To Live (TTL) setting for fully formed security contexts after the first authentication request succeeds.
You will be prompted to download the HTM or HTML file (default document) if you browse http://servername or http://servername/vdir without specifying the file name in the URL. This occurs only if your default document is HTM and HTML files, not for ASP / ASPX
Fiddler trace shows that the request content type is an unknown MIME type and you will be prompted to download a document with no extension which is the default document of the website or the virtual directory.
Unknown MIME Type forcing the browser to download the document
Remove the wildcard MIME mapping or mapping for .HTM / .HTML associated with an unknown MIME type (e.g. Application/myMIME) in the Server level / Master level / File level MIME mappings.
To check the MIME mapping, go to the properties, click on HTTP Headers -> MIME Types.
In one of my case I worked today, the customer had a wildcard mapping as “application/octet-stream.” (Note the . in the MIME type).