wp_inactive_widgets sidebar forgotten, then does notice in /wp-admin/widgets.php

[hakre]

The 'wp_inactive_widgets' is not initalized but used later on.

Can be fixed easily by adding it while the array get's initialized.

Mm, I'm suspecting the suggested patch will break some upgrade/backwards compatibility code we introduced around WP 2.8. It's better use isset() where needed to avoid the notices when there are any.

Replying to Denis-de-Bernardy:

Mm, I'm suspecting the suggested patch will break some upgrade/backwards compatibility code we introduced around WP 2.8. It's better use isset() where needed to avoid the notices when there are any.

Can you please make that suspection concrete with the patch because I do not see the problem here.

Can't recall the specifics, but it had to do with issues upgrading very old sites (prior to 2.5). The widgets were moved around in sidebars, basically. A cursory search leads to these:

#9695, #10092, r11164

Tons more here, for your reading pleasure: #9511. don't forget to look around in related tickets, and related to related tickets.

Alternatively, trust me a take this short short version at face value: the WP widgets API will blow up in your face on changes like the one you suggest, and it's better to add whatever isset() calls are needed until it's rewritten from the ground up.

How many places would isset() checks be required to squash the notices? If it's just a handful, do that.