[imp] error searching body of emails

[Mike Egglestone]

Hello,

I receive an error when searching a large mailbox (such as my Trash  
folder) for a keyword in the body of the emails.
This appears on my terminal shell:

Broadcast message from systemd-journald at intel (Thu 2020-10-29 10:29:12 PDT):

HORDE[32307]: [imp] Call to a member function write() on null [pid  
32307 on line 4436 of "/usr/share/php/Horde/Imap/Client/Socket.php"]

I also receive a red error message in my browser window:
"Error communicating with the server"

This only seems to happen in a large mailbox with 100's of emails.
The error does not happen in smaller mailboxes.

Is this a limit to one of my configuration settings?

Thanks!
Cheers,
Mike