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Hi,

I had the same problem today after update to 2.4.0. I downgraded source code to 2.3.0, but it didn't help. I ended up reinstalling piwik 2.3.0. Provided the same DB details, piwik detected my old database, so I reused it. After that 'reinstallation' it works. Downgrade didn't help, reinstalling 2.3.0 did. Do you want me to try fresh reinstall of 2.4.0?

Piwik was able to gather data about visitors, so the problem existed while getting the data from DB.

@agilob would be great if you could try an update to 2.4.1 or a reinstall. If the problem occurs again, would you mind sending us credentials to your Piwik and FTP so we could debug the issue? Or maybe you could let us know when this problem exactly occurs? Do you get a backtrace?

Update to 2.4.1 was successful and it works fine. afair there was no backtrace.

Do you maybe have any special characters in your MySQL password?

There was a bug in 2.4.0 not reading/saving the MySQL password entry correct if it contained special characters such as "&" or "$". This would explain this behavior and would also explain why it didn't work after downgrading to 2.3.0 since the config probably still contained wrong characters. It is fixed in 2.4.1

Yes, I use keepass to generate passwords with all sets of characters. Thanks for the info.