This is a dumb one that took far longer than I would have liked.

SBS 2008. OWA was spitting out HTTP Error 500.19 – Internal Server Error

The requested page cannot be accessed because the related configuration data for the page is invalid.

It then listed information, owaauth.dll was mentioned somewhere. Should start taking screen shots of these… It also referenced a line of web.config from program files\windows small business server\bin\webapp\sbs web applications, a line containing only . The event log showed an error relating to the DLL as well:

The Module DLL C:\Program Files\Microsoft\Exchange Server\ClientAccess\Owa\auth\owaauth.dll failed to load. The data is the error.

And this one:

Could not load all ISAPI filters for site ‘SBS WEB APPLICATIONS’. Therefore site startup aborted.

The error on the website complained of something being locked.

Searches all talked about 32bit mode vs 64bit, unlocking strings, resetting IWAM and IUSR accounts (though they don’t seem to apply to SBS 2008?), recreating your OWA folders… I did all that for hours with no luck. In the end, it was permissions: owaauth.dll had Authenticated Users granted Read and not Read & Execute. I discovered this by comparing the file to another server. The whole OWA folder was jacked. IISRESET and we were back up.

The moral here is to always remember to check your basics first. Two of my co-workers looked at this for well over an hour before it was passed to me and I won’t say how long I spent working on it before I found this. If the error says that a file can’t be loaded, maybe it actually means that the file can’t be loaded.