An error occurred - No entry or class found for 'Piwik\Plugins\Actions\Menu' after upgrading to 3.0

I’ve just updated from 2.16.5 to 3.0.1 and got a warning message without incidence :
You are not allowed to change the value of the setting “enable_plugin_update_communication” in plugin "CoreUpdater"
After my login, I followed the advice from the system check and removed a lot of files.
Then I logged-in again and got this message : An error occurred - No entry or class found for 'Piwik\Plugins\Actions\Menu’
From the apache logs, it could also be : Piwik\Plugins\Referrers\Menu
I unzipped again piwik but the Menu.php files for those 2 folders don’t exist anymore in Piwik 3.0.x. (so only in 2.x).

Do you have any idea how I can get rid of this error ?

For the moment, the workaround is to enable the development mode, that disables the integrity file check (in config/global.ini.php and section [Development]).

Thanks in advance.

You can ignore this error for now

I am having the same issue. I have updated, removed the suggested files and folders and now I cannot reach my backend. I am getting the error message
An error occurred - No entry or class found for ‘Piwik\Plugins\Actions\Menu’

How can I enable development mode in order to get into the backend?

P.S.: Found the development setting in global.ini.php and can access the backend

Will I now have to run piwik in development mode all the time?

Phew … got it running by downloading a version of piwik 2.17.1 and uploading Menu.php to a bunch of folders that seemed to be missing the file. Now I can access the backend in normal mode again.

P.S.: I like the look of the new backend … thanks for all the work!

I just upgraded our test server to 3.0.3 in preparation for upgrading our production server soon and ran in to this problem as well. I removed all files suggested under System Check but then Piwik stops working and as soon as I log in either as a superuser or a regular user I get this error message:

After restoring the Menu.php files from the plugins complaining as the above image the system check looks like this:

Should I just leave it like this and will the same thing happen when I’m upgrading our production server or could ther be something different with the test installation?

Best regards

One more thing, I found this issue on GitHub suggesting this was fixed, could it matter from which version we upgraded?

I’m getting the same thing after an upgrade from 2.17.1 to 3.0.4 and deleting all the recommended files shown in the file integrity check. After reading some of the other posts, I figured out I had to run the console command core:clear-caches after deleting the files and that solved the issue.