Piwik plugin not installed

I realized that in OJS 3.1 Piwik plugin is not being installed when install procedure was initiated via Plugin gallery. Please check. In some cases it is misreported that it is installed although it is not installed. manual installation of Piwik plugin solved issue. Please check that.

Hi @vvucic,

Is it possible that you had the Piwik plugin installed in a previous release, then upgraded, leaving Piwik in the database (in versions) but not on the filesystem (in plugins/generic/piwik)?

Alec Smecher
Public Knowledge Project Team

IN one installation it freeze when I click on Install plugin. There was no Piwik plugin installed at all.
I helped in this thread

and he realized that there is no plugin although it was reported that plugin is installed and update.