[Koha] Label export failed to load PDF document

[Caitlin Kleinpaste]

I'm using 3.20.03.000.

When I try to export barcode labels using the label creator, instead of
exporting a pdf is gives me an error saying "Failed to Load PDF Document".

I've never had this issue before and have been using the label creator for
a year.  It's only a problem for barcodes, not spine labels.  Also only
when exporting a pdf, not for xml or csv.

We create a batch using barcodes copied from a excel spreadsheet.  (We've
also copied them out of word-- the formatting doesn't make a difference.)

This particular batch has 284 barcodes.  We have tried it with fewer-- it
was ok with 2 and 10, but not with 9 or any number higher than 10.

Any ideas of what it might be or other things that we could try would be
appreciated.

Thanks,
Caitlin Kleinpaste