Operating system Ubuntu Linux 22.04.2
Webmin version 2.101
Usermin version 2.001
Virtualmin version 7.7
Cron root@host /etc/webmin/status/monitor.pl
WARNING: MYSQL_OPT_RECONNECT is deprecated and will be removed in a future version.
my site runs wordpress and there is no instance of ‘MYSQL_OPT_RECONNECT’ anywhere in the entire www root, so i don’t know what’s generating these constant notices every 5m
That looks like a php mysql driver problem … use google to search the problem out … if you have different versions of php installed switch to a different version and see if the error persists
looks like several people are having this problem as of late, though i don’t know what the cause is
i switched from php 8.0.30 to 8.1 and 8.2 and in both cases my website won’t load - internal server error
disable all plugins (if any) and retry if it works add them one by one until you get a failure
I think this post could explain the basis of the problem:
The warning as an “error” only started after yesterday’s php 8.1/8.2 updates. So I assume they have decided that the deprecated feature is now indeed an error, and monitor.pl will need modification.
Sorry, forgot to mention that this seems to only be on Ubuntu 22.04.3, not on Debian 12.
I have the same problem. It is not related to Wordpress or anything, the error is coming from the cronjob running /etc/webmin/status/monitor.pl as the message says. So this is a problem with Perl and not PHP.
I’m getting this every 5 mins by email, but it only started at around 6:30am GMT this morning, which I find odd. I don’t have auto updates turned on.
Just edit your root crontab for a temporary solution that is not annoying you. There is a line there related to monitor.pl
0,5,10,15,20,25,30,35,40,45,50,55 * * * * /etc/webmin/status/monitor.pl
Background
Last night Ubuntu released a patch for libmysqlclient21 which includes a MySQL update that affects Perl.
/etc/webmin/status/monitor.pl is run every 5 mins and calls /usr/share/webmin/status/monitor.pl which then calls /usr/share/webmin/status/mysql-monitor.pl which in turn calls /usr/share/webmin/mysql/mysql-lib.pl and that shows that the entire way that Webmin is authenticating with MySQL is via the deprecated call 
Workarounds
Option 1) Roll back the affected package and hold it…
$ sudo apt list -a libmysqlclient21
libmysqlclient21/focal-updates,focal-security,now 8.0.34-0ubuntu0.20.04.1 amd64 [installed,automatic]
libmysqlclient21/focal 8.0.19-0ubuntu5 amd64
$ sudo apt install libmysqlclient21=8.0.19-0ubuntu5
$ sudo apt-mark hold libmysqlclient21
Option 2) Edit the cron to grep out the warning
$ sudo crontab -e
change
0,5,10,15,20,25,30,35,40,45,50,55 * * * * /etc/webmin/status/monitor.pl
… to…
0,5,10,15,20,25,30,35,40,45,50,55 * * * * /etc/webmin/status/monitor.pl 2>&1 | grep -v "MYSQL_OPT_RECONNECT is deprecated"
Hopefully a fix will be out soon
@Dogsbody_Technology - just wanted to thank you for digging into this and offering solutions
personally i’ll wait on the fix and just use option 3): auto-trash mails with MYSQL_OPT_RECONNECT in the body 
Thanks. I chose option 2. How will I know when to do unhold?
You won’t know. You will either have to wait for someone to post here or keep checking and rolling back I’m afraid