After updating PHP to version 8.2, an error occurs when updating the ad. But the ad is updated, even though time passes. If you use the sigma template, no error occurs; only warnings appear in the logs.
I use my own template, which I wrote based on the Sigma template. Help me figure this out

Try to update your osclass, seems like some very specific issue.

The latest version of Osclass is installed, I updated it through the control panel.

In such case, go to itemactions.php
find line like this
    $flash_error .= ((!osc_validate_text($aItem['address'], 3, false)) ? _m('Address too short.') . PHP_EOL : '');
and fix them in way:
    $flash_error .= ((!osc_validate_text($aItem['address'] ?? '', 3, false)) ? _m('Address too short.') . PHP_EOL : '');

so you adding ?? ''