Print multiple packingslips to PDF results in corrupt PDF file

I have recently upgraded to nopCommerce 4.60.2 and I notice that when trying to select multiple orders and then print the selected packingslips all into one PDF, the PDF is generated but the PDF can not be openend. It throws an error that it failed to load the document.
If I select the same orders and print every packingslip as a separate PDF, I can open all of them without any issues.

I have this on both my test-environment and on my production environment.

Just tested and worked fine for me
When selecting multiple Orders (or All orders) it creates a Zip file of the orders and opens the zip file
Are you see the Zip file in downloads

Hm ok, that is strange. It does not create a zipfile. I just get the .pdf directly as a download.

Ok, just renamed the .pdf file to a .zip and then it can open and extract the .zip file with all the .pdf's inside....
So, for some unknown reason I get a .pdf file as a download that should be a .zip file....

It only happens on my instance when I have multiple orders, and select only a few and then select the button to Print only the selected orders.
Then it generates a packingslips.pdf instead of a packingslips.zip.
I just checked the code and I do not see any issues here, but did not debug it yet. Also no other plugins installed that should do anything with the PDF export.

Thanks a lot for reporting. We'll fix this issue soon

We fixed this issue, details can be found in this commit