Just a quick entry for webmasters or clients who have a problem logging in to their website.
I fixed an issue where wordpress failed to log me in and gave no error or clue to why. Proof in concept that sometimes websites just change without a clear reason why.
I tried about 10 blogs which suggested causes such as cookie corruption,redirect issues, folder permission problems and PHP errors, none of which worked for me.
For me it was 2 tables which had lost their Auto_Increment setting and had changed to a default=0 value for the unique table ID. That meant that WordPress was unable to do something with the user_meta and user tables – presumably updating it on login.
Anyhoo, changing those tables to auto_increment the ID allowed me to login again. I am guessing that the error crept in during a migration of Mysql and for some reason only just reared its ugly head…
I hope that helps someone out there using this terrific platform 🙂