The errors indicate that there is a problem with the theme and how it’s loading widgets. You need to correct that.
PHP display of errors can be controlled several ways, so it would be hard for me to tell you exactly how to turn it off.
There may be a php statement somewhere that looks something like
there could be a statement in you’re htaccess file that looks something like this
php_value display_errors On
display_errors could be on by default on your host
errors are displayed if you have this statement anywhere
I’m sure there are others I missed, the theme could be turning it on, and others.
The problem could be cause by a plugin. Disable plugins and switch to a default WP theme and see what clears up the problem. Something is doing something in a way that has been deprecated by WP, do you have an old plugin installed that has not been updated in a while? Has the theme been updated recently?
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