Resolved Roundcube mbstring issue with Litespeed - error 500

[Hostarts]

Server operating system version

CloudLinux 7.9

Plesk version and microupdate number

18.0.51.1

Hello

The issue appears on its own since introduction of the latest version 18.0.51 we have been getting these cases related to litespeed and roundcube, we tried checking if the issue is related to CageFS but it does not appear to happen due to that.

Swtiching to apache resolves the issue but at the same time server will suffer from higher load at some point of the day.

```
17-May-2023 10:51:04 UTC] PHP Fatal error: Call to undefined function mb_internal_encoding() in /usr/share/psa-roundcube/program/lib/Roundcube/bootstrap.php on line 86
[17-May-2023 10:51:04 UTC] PHP Fatal error: Call to undefined function mb_internal_encoding() in /usr/share/psa-roundcube/program/lib/Roundcube/bootstrap.php on line 86
[17-May-2023 10:51:05 UTC] PHP Fatal error: Call to undefined function mb_internal_encoding() in /usr/share/psa-roundcube/program/lib/Roundcube/bootstrap.php on line 86
[17-May-2023 10:51:06 UTC] PHP Fatal error: Call to undefined function mb_internal_encoding() in /usr/share/psa-roundcube/program/lib/Roundcube/bootstrap.php on line 86
[17-May-2023 10:51:06 UTC] PHP Fatal error: Call to undefined function mb_internal_encoding() in /usr/share/psa-roundcube/program/lib/Roundcube/bootstrap.php on line 86
```

 

[Peter Debik]

The mbstring package is missing for PHP handler where Roundcube is running under. Install the php-mbstring package of necessary version(s). In the Plesk supplied PHP versions this is available by default. I am not sure what the situation on your system is that it is missing there. Maybe some custom PHP version that was installed along the road?

 

[Hostarts]

The MBstring is already available and installed :

rpm -qa | grep plesk-php74-mbstring
plesk-php74-mbstring-7.4.33-1centos.7.221109.0743.x86_64

Any other clue ?

 

[Peter Debik]

In the PHP installations provided by Plesk all necessary PHP modules are included. But your error message above clearly states that a function is missing. This leads to the hypothesis that your Roundcube is not using any of the PHP versions provided by Plesk. Please have a look at this KB article from where you can derive places where to check how your Roundcube is set up, e.g. which PHP it uses.

https://support.plesk.com/hc/en-us/articles/12377961662743

You also mentioned that it only fails on Litespeed. How was Litespeed installed? What PHP is used in their configuration for the webmail subdomain?

 

[Peter Debik]

Another idea that comes into my mind is that CloudLinux has a caged PHP/PHP selector. That won't work right with Plesk PHP. Either one or the other, but not both. The PHP version used through Litespeed might be the caged PHP from CloudLinux. That will need to be checked on the server.

 

[Hostarts]

After further checks the issue appears to have been documented on this page :

litespeed_wiki:plesk:webmail_500_error [LiteSpeed Wiki]

www.litespeedtech.com

problem resolved.