Upgrade failed – debug warning

I reset the site now, so there is no error warning anymore. BUT I am hesitant to update the Plugin again. Can I delete it via FTP and upload the new version without loosing its data?

With the second trial, I was left with a completely destroyed database. ??

I re-imported a backup, now the site is running again – and at least there is no visible error on the frontend anymore. But in the backend it still persists:

Notice: register_uninstall_hook was called incorrectly. Only a static class method or function can be used in an uninstall hook. Please see Debugging in WordPress for more information. (This message was added in version 3.1.0.) in /usr/www/users/nattex/__naturtextil_2018/wp-includes/functions.php on line 4161

Warning: Cannot modify header information – headers already sent by (output started at /usr/www/users/nattex/__naturtextil_2018/wp-includes/functions.php:4161) in /usr/www/users/nattex/__naturtextil_2018/wp-admin/includes/misc.php on line 1126
What can I do to get rid of this?

• This reply was modified 6 years, 2 months ago by axelhess.

One more time. The site was behaving strangely, so I restored from a backup from 5 days ago, before I made any changes. I had several plugin updates pending, but this time I ONLY updated Ultimate Member from the plugin site. No problem yet – but I again got a notice I have to UPGRADE this plugin, with a button. The moment I clicked onto the upgrade link, the error message in the backend was there again!

One more time I clicked onto “Run”. This time the upgrade went through, it seems. No error anymore-yet.

But hey, folks – why, did this have to happen? As it seems to me: Poor programming. You can do better…

Hi @axelhess,

Thanks for letting us know.
We recommend disabling all plugins while doing the DB upgrade.
It looks like you’ve had a conflict with your caching plugin, please make sure to clear cache and exclude Ultimate member pages from the cache.

Regards.