Well it wasn’t really solved over at the Jetpack team. I think the devs were informed, but they took the disussion on the e-mail channel and closed the issue.
However the error still persists and only your suggestion to switch from PHP to the HTTP mode allows me to use both plugins without running into that error.
Hi there,
thank you very much for the hint!
Actually I was using WP-Piwik in PHP mode. I switched to HTTP mode and I can not reproduce the error this way. So I will keep using HTTP mode for now. This way I can activate the Jetpack comments again.
Let me know how I can help to find the reason why PHP mode is not working anymore (at least it is not working on my setup).
FYI: I am using the default WordPress Twenty Sixteen theme.
Deactivating the other plugins had no effect. Jetpack comment box always shows the reported error.
Standard comment box works fine.