Admin sub-menu item doesn’t show on mouse hover after upgrade to 5.8

I’m unable to replicate such issues on my site, 5.8.2 with Twenty Twenty-one theme and no plugins. When you tested with such a configuration we should both be experiencing the same results.

There could be something about your server or browser configuration that’s preventing all the usual resources from being utilized. Check your browser console and the server error log for additional clues. Also check the Site Health admin screen for flagged issues. Use the network developer tool in your browser to verify all requested files were served with a 200 status.

Hello,

Thanks for your reply, this is what chrome inspect shows:

Uncaught SyntaxError: Unexpected token ...
index.php:1028 Uncaught TypeError: Cannot read property 'setLocaleData' of undefined
index.php:1034 Uncaught TypeError: Cannot read property 'setLocaleData' of undefined
common.min.js:2 Uncaught TypeError: Cannot read property '__' of undefined
index.php:1051 Uncaught TypeError: Cannot read property 'setLocaleData' of undefined
url.min.js:2 Uncaught SyntaxError: Unexpected token {
index.php:1071 Uncaught TypeError: Cannot read property 'setLocaleData' of undefined
index.php:1093 Uncaught TypeError: Cannot read property 'setLocaleData' of undefined
edit-comments.min.js:2 Uncaught TypeError: Cannot read property '__' of undefined
index.php:1104 Uncaught TypeError: Cannot read property 'setLocaleData' of undefined
postbox.min.js:2 Uncaught TypeError: Cannot read property '__' of undefined
index.php:1123 Uncaught TypeError: Cannot read property 'setLocaleData' of undefined
dashboard.min.js?ver=5.8.2:2 Uncaught TypeError: window.wp.deprecateL10nObject is not a function
index.php:1135 Uncaught TypeError: Cannot read property 'setLocaleData' of undefined
index.php:1147 Uncaught TypeError: Cannot read property 'setLocaleData' of undefined
updates.min.js:2 Uncaught TypeError: Cannot read property '__' of undefined
index.php:1162 Uncaught TypeError: Cannot read property 'setLocaleData' of undefined
index.php:1201 Uncaught TypeError: Cannot read property 'setLocaleData' of undefined
color-picker.min.js:2 Uncaught TypeError: Cannot read property '__' of undefined
a11y.min.js?ver=0ac8327…:2 Uncaught TypeError: Cannot read property '__' of undefined

jQuery.Deferred exception: Cannot read property ‘__’ of undefined TypeError: Cannot read property ‘__’ of undefined
at HTMLDocument.<anonymous>

jQuery.Deferred exception: postboxes is not defined ReferenceError: postboxes is not defined
at HTMLDocument.<anonymous>

jQuery.Deferred exception: Cannot read property ‘sprintf’ of undefined TypeError: Cannot read property ‘sprintf’ of undefined
at HTMLDocument.<anonymous>

load-scripts.php:2 Uncaught TypeError: Cannot read property ‘__’ of undefined
load-scripts.php:2 Uncaught ReferenceError: postboxes is not defined
load-scripts.php:2 Uncaught TypeError: Cannot read property ‘sprintf’ of undefined

Also there no error in WP admin (health tool) and in Cpanel log.

It’s unclear what the root cause is, it appears to be your theme, but could be due to a plugin. Further testing is required to narrow down the root cause. Switch to Twenty Twenty-one theme and deactivate all plugins. There should no longer be any console errors.

Restore your normal theme and plugins, one at a time, until the errors return. The last activated module would be the cause. Be cognizant of caching confusing test results. Flush cache or do a hard refresh (Ctrl+R) after each module reactivation.

Hello again,

Thank you,
After spending time some hours, I found that the issue is in old version browsers (like Chrome, Firefox,…), as we still need to use Windows XP and they are not running with the last versions.
Do you know any method to edit some core files (in WP version >= 5.8) to working without problem in the older browsers?

XP?! Yikes ?? I fear the changes needed could be quite extensive to back support older browsers. Doing so could make support for current browsers at the same time difficult (or maybe even render some recently added backend features inoperative regardless of browser version). The right approach would be to create a plugin to contain the modified script files. Then deregister any that are pre-registered by default by WP core and register the modified scripts under the same handles. Also, in any theme or plugin files that register or enqueue scripts, ensure they are using your modified versions.

Or you might simply directly edit the relevant files, which would then mean further WP updates would be impractical. But if you’re not updating the O/S anyway…

Perhaps the simplest and most practical approach would be to revert WP back to a version that does support your browser. Older WP versions are readily available, but the same cannot be said of some themes and plugins which would also need to be reverted.

Thanks for your explantation.

Yes, we still need to use Windows XP, and there are some difficulties to use it nowaday.

About the plugin, it will be great if we could have some plugin like that, I don’t know if I have to do something for or not but if you see something to solve this problem in the future, please let us know.

We are using WordPress v5.7.4 which is still working on Windows XP without any problem.

Hope that our discussion being useful for another WordPress users and we wish you all the best with health.

Thanks again and regards.