I find the its the use of certain characters in the file name or the length of the file name....trying renaming using basic alphanumeric and keep it short.
Hello there, phoneixarising.
Thank you for sharing your suggestions for other users here in the QuickBooks Community. Affected users may try this out to isolate the problem with attaching a document.
For additional insights, I'm also adding the article I recommend in case someone needs it: QuickBooks Attached Documents: FAQs and common issues.
Thanks for dropping by, the QuickBooks family wish you a wonderful rest of your day.