hi after I upgraded my moodle site to 4.4 when a new user signup to my moodle site at the end of signup process and on create my new moodle acount user get an error message saying
Is it different from https://moodle.org/mod/forum/discuss.php?d=458073#p1839629 ?
I see, unfortunately that thread was hijacked by somebody.

I see, unfortunately that thread was hijacked by somebody.
Yes it is a different problem
The other problem I couldn't solve and I have to restore my home directory and download noodle to new folder and did upgrade as usual and copied plugins one by one
What is the status now, where you able to fix the issue?
Yes solved as following:
the problem was solved by changing the data base tables with utf8mb4_unicode_ci collation
the problem was solved by changing the data base tables with utf8mb4_unicode_ci collation
I enabled debugging but nothing appear in debugging
How did you enable debugging? Because I'm sure you would see more details with debugging enabled.
site administration-> development ->debuging -> show all debugging messages
And Display debug messages? What is that set to?
I also now discovered that the same problem happen on manually adding new user
thank you friends
the problem was solved by changing the data base tables with utf8mb4_unicode_ci collation
the problem was solved by changing the data base tables with utf8mb4_unicode_ci collation