Sitecore Swamp

Issue:

It's quite common scenario for a Sitecore consultant to spin up a environment from existing implementation. After you reset password for the Admin user, you still have the error prompt on your face:

Investigation:

And you checked in the database, the user ("B09BBCDE-9B3C-4DCD-B69E-67F615CE01E9") is not locked or not approved. Then there's another place can explain this:

<sites>

...

<site name="login" virtualFolder="/sitecore/login" physicalFolder="/sitecore/login" enableAnalytics="false" database="core" domain="custom" disableXmlControls="true" />

...

Resolution:

The default domain has been changed, and you have to login with sitecore\admin rather than admin, or change domain back to sitecore.