Subcategory 1 already exists

Support & Bugs
#1

What das that mean?

Error in Piwik: Subcategory 1 already exists

[Wed Jan 25 13:54:33.539277 2017] [:error] [pid 27026] [client ***] Error in Piwik: Subcategory 1 already exists, referer: https://***/piwik/index.php?module=MultiSites&action=index&idSite=1&period=day&date=2017-01-02&updated=1

#2

Got it

Truncate Table PREFIX_user_dashboard and it works.
And add primary-Key to login and name.

Looks like after Piwik Update the Keys where lost.