We generate tickets from email imports. It appears embedded pictures in the emails are causing this. They come in as un named linked files - delete them and the error goes away.
@nickp , I am the developer of the new module (from 2024) Ticket Plus & Helpdesk, and what you have explained here suggests that I should review the case you have exposed: that one of the messages in a ticket thread contains an embedded image!
It’s unlikely that this would happen if the person who embedded the image did so by “copying and pasting” it from an email, but if they did it with an HTML tag like <img /> then it could happen. And in these cases, it would be interesting if the image could be previewed when viewing the ticket.
There’s also the case where someone has simply pasted the URL of an image hosted on another website into the body of the message. But certainly, the web interface allows attaching images (and other files) to a ticket comment (in my module’s interface), so I highly doubt anyone would use it that way. But I will check if I can implement something that improves the usage in those cases.