I have had a strange error today in my dev lab environment. First I recognized that I could not select users from the People Picker:
Sorry, we’re having trouble reaching the server.
Second I realized that I was not able to use any function that belongs to WCF web services such as the SharePoint REST API, e.g. at http(s)://<server>/_api/web.
Using Fiddler I found this behavior:
HTTP 404 NOT FOUND on /_vti_bin/client.svc/ProcessQuery
Same for /_vti_bin/client.svc/web which is the same as /_api/web.
Search the web I found some hints regarding this error in SharePoint. But nothing worked.
Than I created a own web service “service1.svc” with a simple method in it and placed it in folder <SP-Hive>\isapi where the virtual folder “_vti_bin” is located on the file system.
Result: I could not call my own web service too. Same result: NOT FOUND.
Than I search the web for “WCF 404” and found some hints to “HTTP Activation” feature of Windows Server OS. Of course this was activated for .NET 3.5 and .NET 4.5.
So I deactivated the “HTTP Activation” feature of .NET 3.5 and .NET 4.5 and re-enabled one by one (1st .NET 3.5, 2nd .NET 4.5 ) them after deactivation.
After that I did a IISRESET. – Than everything works again as expected. 🙂