naser44 If it occurred after activating the extension, it is likely to be an issue with that extension.
Extensions are made by community and some of them might be buggy after updating Flarum.
But I recommend you to wait for @Sanguine , he has access to the logs and hopefully he'll find anything that will help us. But I'm pretty sure that the extension is not compatible with Flarum at the moment. In that case, you should contact the extension's author for a fix.
Edit: I have checked your forum, registered an account and changed my language to English and I can confirm that it is likely to be a bug with the Arabic extension.