I am still searching for the solution to this problem. And have searched the forum where people have reported a similarly/same error code. Yet the solutions provided are not helping me out. Like the post below Costume block Manager Blocks cannot be activated after upgrade to OJS 3.2.0.1 - #21 by Felixmail2015.
I have only one language (English) in my settings since the beginning and never changed it for the last three years.
Any expert opinion where to look at for the solution as this error is appearing like 10 to 15 times every minute in my PHP error log.
Thanks