Issue Admin panel freezes after login

[tapulator]

Ah, another week, another bug. *g*

After logging in to the admin panel I'm redirected to the homepage (/smb/web/view) which renders fine, but the UI freezes.

Browser developer tools show a failed request for document view, server responds with status 500.

Cleared the browser cache and checked these error logs, but they don't contain any (recent) errors:

• /var/log/sw-cp-server/error_log
• /var/log/apache2/error.log
• /var/www/vhosts/system/myserver.com/error_log
• /var/log/nginx/error.log
• /var/www/vhosts/system/myserver.com/proxy_error_log
• /var/log/plesk-php73-fpm/
• /var/log/plesk-php73-fpm/

Log /var/log/plesk/panel.log on the other hand contains an interesting entry:

Argument 1 passed to Plesk\PartnerCentral\ConsentGet::send() must be of the type string, null given, called in /opt/psa/admin/plib/NewsletterSubscription.php on line 64

To give you some context:

I'm using Plesk Obsidian 18.0.31 Update #1 on Ubuntu 18.04.4 LTS. After installing PHP 7.4 via apt I detected the problem described above, though not immediately, so I'm not sure if there is a relation. And there's another issue I'm currently experiencing.

Any hints on debugging?

 

[Bitpalast]

Have you tried
# plesk installer --select-release-current --reinstall-patch --upgrade-installed-components
# plesk repair installation
?

 

[tapulator]

Thanks, but that didn't help: The repair log shows no errors. Still, the problem persists.

 

[Bitpalast]

When you say the UI freezes, what does this exactly feel like? You say that the page is loading, but obviously AFTERWARDS you cannot click on anything?

Have you tried it with a different browser?

 

[tapulator]

When you say the UI freezes, what does this exactly feel like? You say that the page is loading, but obviously AFTERWARDS you cannot click on anything?

Actually, the viewport freezes, like an invisible layer had been put on top. The UI isn't responsive at all, no reaction to clicks, hovering or window resizes.

The "reload page" button in the browser bar keeps spinning. And apparently the CPU get's hogged, because the fan cranks up.

I get the feeling that the admin panel is trapped inside an infinite loop.

The described behavior occurs on Chrome 86.0.4240.111.

Have you tried it with a different browser?

Good idea! Firefox 82.0.3 seems to work fine.

 

[Bitpalast]

This is clearly a JavaScript issue. Have you tried to clear Chrome's cache and to clear all cookies?

If the problem persists with Chrome afterwards: I have only seen similar issues on systems there have been compromised by malware. A first approach to solve this problem is to disable, even better remove all add-ons that your Chrome browser is using. Plus, do a thorough antivirus check, meaning run a check with some second-opinion malware scanner in the "safe mode" of Windows (checking it with your default antivirus software and in normal operating mode won't find all). With a clean system and fresh Chrome installation the issue should not occur, then go ahead and reinstall the add-ons one by one, test Plesk functionality in between each step to identify the add-on that is messing with it.

 

[tapulator]

Firefox 82.0.3 seems to work fine.

Have to correct myself: The familiar error message appears at the bottom of the page in form of an injected HTML page. I attached a screenshot for better understanding. This behavior can also be seen on other panels.

This is clearly a JavaScript issue.

Not in the first place. Chrome and Firefox just seem to handle the server-sided error differently.

My guess is some data inconsistency in Plesk Admin's database tables, somewhat related to the user's newsletter subscription status.

 

[Bitpalast]

For the 500 error, probably an email address is missing in some dataset, e.g. your own admin profile. But that type of error is a server-side issue and won't lead to a freezing screen on the browser.

Meanwhile you have performed the malware scan of your system as described in my post above? In Windows safe mode with a second-opinon software (e.g. the free tool from Hitman Pro from Sophos)?

 

[tapulator]

@marlies' hint also fixed this server issue.

For the client side:

Can't reproduce the UI freeze, and the accompanying server error, anymore. But I'm not really sorry for that. *g*

What I can say to @Peter Debik's suggestions is:

• Browser add-ons: I don't have any fancy browser add-ons installed. The error occured even on one box where only uBlock is installed, which shouldn't break your web app. Otherwise it's a sign for bad design on vendor's side.
• Malware: I tried to use the admin panel on different Linux machines, so a malware infection is not very likely the source for the UI freezing. I will run a scan and report back.

To this point it looks like non-robust error handling / a missing killswitch to me. The JavaScript awaits a certain response but get's some malformed response, probably in form of the injected error page. Maybe Chrome tries to evaluate the response over and over again (no killswitch), while Firefox simply gives it just a browser-defined amount of tries ("implicit" killswitch).

 

[tapulator]

I will run a scan and report back.

Ran a full malware scan with LMD on one of the boxes experiencing the UI freeze: No malware found, fortunately.