Please how can i solve this problem on my Wordpress site
Undefined variable: error in /home/sitename/public_html/wp-admin/theme-editor.php on line 277

techliteup:
Please how can i solve this problem on my Wordpress site
Undefined variable: error in /home/sitename/public_html/wp-admin/theme-editor.php on line 277

I take it this is from your error log? If yes, it seems like a syntax error in your theme. Two things; you can either have do a conflict check or debug by deactivating or temporarily switching between your current theme and another.

Another thing worthy of note is to undo whatever changes you did.

In the event that you are not sure, simply locate your installed theme file on your PC, locate the specific file, copy its content and replace with the one in your root folder.

In the event that you can't figure this out, you can get in touch.

techliteup:
Please how can i solve this problem on my Wordpress site
Undefined variable: error in /home/sitename/public_html/wp-admin/theme-editor.php on line 277

what where you doing before you encountered this error?

( it seems you were trying to edit a theme file )

also the error log you posted is not complete