Google Analytics Importer: Unable to import OAuth Client configuration


I am trying to import a website from Google Analytics into Matomo, however, I’ve got stuck on step 2.2.3 from

When I try to import the OAuth Client configuration file, either as a file, or pasting its contents into the Configuration Text field, after pressing Save, the page gets reloaded to an empty form without any message or visible change.

So far I have failed to locate any hint pointing to whatever may have gone wrong: there’s nothing in webserver’s access/error log, nothing that seems relevant in Piwik log (even when increasing verbosity in config.ini.php to DEBUG), nor do I see anything interesting in the Firebug network requests log (like failing HTTP codes).

AFAICT the OAuth Client configuration JSON file that I have received looks sound.

For the purpose of using the GoogleAnalyticsImporter plugin I had to enable the Login plugin (if I remember correctly – we normally use LoginLdap). I tried to temporarily disable LoginLdap, in case it is causing the trouble, but that didn’t seem to change anything. I also believe I meet all the requirements mentioned in the importer docs page.

I am running latest Matomo 3.13.6 with latest Google Analytics Importer 1.4.0.

Any hints as to what I might be doing wrong or what should I try?

In case anyone stumbles upon this, see