when I try to access the admin panel of the site then show me this error and site also not open show the critical error message.
it comes today. and not update the WordPress version.
Try reinstalling wordpress.
Please do mention your website
I use this site for practice of wordpress not more plugins use just Yoast for SEO,classic editor,elementor, etc this is the site
http://dilshadahmad.epizy.com/
Okay seems a internal error, you might consider a backup from softaculous and then reinstalling wordpress.
I guess it will work
then can I access my admin panel of site?
because there also show critical error. 
Yes after reinstalling you can.
Well have you updated your wordpress recently using wp updater in wp-admin?
This is no internal error. You simply have to read the guide provided by @anon77371365:
how can u be that sure?
I’ve experimented and studied WP and used it for a long while to know it’s errors, and I’m 100% sure it’s nothing got to do with Internal Server Error.
okay.
If it was Internal Server error then you would get blank screen / 500 Error
Well you guys are taking it wrong.
I said Internal Error! Not Internal Server Error.
I meant to say error in terms of files/core of wordpress.
I’m too a experienced wordpress professional. This happened with me too.
We can see too. U have given us URL and I have myself faced this error.
I m damm sure u did something from wordpress dashboard like updating anything theme plugin or core.
Critical errors come only after some fault or trigger
Or may be installation corrupted
yep I think also it happen because I try to update the wordpress but not happen so after sometime it show me this error.
On infinityfree you should update wordpress manually as there is a strict 10 MB max upload size limit due to which the update wasn’t completed and you started to have this error.
download wordpress latest version from https://wordpress.org and then extract it on your PC
after that upload it through FTP or you can also split it into parts (not from winrar splitter).
Make zip files of 9 MB (less than 10 MB) each and upload those files and then extract them or simply use FTP and upload all the contents in wordpress folder to your site.
It might fix the problem as core files are only one that are corrupted with that update process.
Activate debugging.
In functions.php you will get the type of error and it will tell you which function and which file have failed… it can find out what kind of error you have.
To solve this:
1 - Wait for infinityfree to update wordpress
2 - Remember to update the plugins and their templates so that it does not come out.
3 - Upload it manually
It is better that the manager has everything well configured.
Let’s find the error :)!
