Why does an error occur when merging multiple pdfs?

Question

PHP

Merge files (pdf) worked on the server, after moving to a new one, such an error appeared

[setasign\Fpdi\PdfParser\CrossReference\CrossReferenceException]
Invalid data after startxref keyword. (257)
...
#7: Clegginabox\PDFMerger\PDFMerger->merge(string, string)

the same files are merged on the old one, not on the new one, the script is the same. This is probably related to the server, but I don’t understand where to dig