If you received an e-mail about your WordPress site like this:
Since WordPress 5.2 there is a built-in feature that detects when a plugin or theme causes a fatal error on your site, and notifies you with this automated email.
In this case, WordPress caught an error with one of your plugins, WPtouch Mobile Plugin.
This can probably be safely ignored. The web server ran out of file descriptors. It was configured for a million but the total amount needed exceeded that today. I believe there may be a file descriptor leak in libsasl but until a fix is made available I’ve bumped it up to 4,000,000 which hopefully will suffice.