API keys not working after upgrade

[claes.hermansson_6271]

We just upgraded ProGet from 5.0.7 to 5.1.19 and now pushing NuGet packages has stopped working with error message "Forbidden ... Response status code does not indicate success: 403 (Invalid API key)."

I have read all documentation and can't figure out why. Same error with old keys and newly registered.
API key logging is on but no logs are produced, have also tried to enable Debug mode in ProGet but can't get any more information.

Product: ProGet
Version: 5.1.19

[atripp]

There were no changes that would have caused this, but common things to check are

• Make sure WebDAV or another HTTP-filter didn't get enabled or installed by mistake; this will block certain requests from ever reqching ProGet

• Grant anonymous user full permissions to make sure the connection works; often times, the error is between ProGEt and the client

• Once it works with anonymous, start restoring privileges/API keys until you identify which configuration is causing it

[claes.hermansson_6271]

The problem occured because some authentication behaviour is changed in ProGet, the solution was to alter the syntax of the Feed API user from [domain]\[userid] to [userid]@[domain].[top domain]. The old syntax worked before upgrading, no hints in ProGet that this had changed.

[thoven]

As a followup, it's worth mentioning that this occurs specifically when directory providers are switched. The "Active Directory (New)" user directory requires the user@domain.tld format, so switching from the previous "LDAP & Active Directory" user directory (which supported netBIOSdomain\user) no longer can impersonate.