Every now and then, we run into weird and unprecedented WordPress problems and the below scenario presents one that we encountered in October 2020.
All of a sudden, many of our clients were unable to log on to their WordPress sites. This also affected our WordPress admin accounts. WordPress just said: ”Invalid username or password”.
Resetting password using MySql commands did not help.
Most of the clients sites use Cloudflare for added speed and security, so we disabled Cloudflare to see if the problem was caused by their caching – It was not.
We then started going through all active WordPress plugins to see if any of them could be involved in the login problem. Using “divide and conquer” search is a fast way to narrow down the number of suspects.
Divide and conquer:
• Disable half of the plugins
• Test the site
• If it works, we know which half of the plugins is causing the issue.
• Rinse and repeat
In our case, it turned out that the Google Captcha plugin was the culprit. After disabling it, the problem was gone.