invoice can't be accessed in backend

[p.barg]

Hello,

in one of our shops we have a problem with PDF invoices: the invoices are generated, placed on the server and e-mailed correctly, but can't be accessed
in the backend. If the corresponding icon is clicked, an error is shown that the connection is interrupted. I've transferred the installation to a local server
where the problem doesn't exist. I therefore suspect, that it is a problem with the setup of the server.
Any hints here as to what might cause this issue?

Joomla! 3.9.23, VM 3.8.8, PHP 7.4.14

Thanks, Petra

[AH]

Check server folder ownership and permissions

[p.barg]

Permissions are all ok (eveything green) and I haven't changed anything there and the installation runs perfectly with a different provider...
The invoices are stored correctly on the server, so the generation of the PDF seems to work ok. Just the access in the backend
is the problem.
I figured out that in the URL that is called the problematic part seems to be "&format=pdf":
/administrator/index.php?option=com_virtuemart&view=orders&task=callInvoiceView&tmpl=component&virtuemart_order_id=3&layout=invoice&format=pdf&d=47&invoiceNumber=21020261FZ011

If I remove that part from the URL the invoice is displayed (although not correctly of course).

But I'm completely at a loss what could cause this issue...

[AH]

I reviewed the URL and this is perfectly correct.

You may need to see if you are being restricted via your web host - you might be better discussing this with them - they should have the logs and be able to diagnose

[p.barg]

Thanks for your answer.
We will contact the provider tomorrow and hope that they can find the problem.
If so, I'll share the results here.

[AH]

Thanks - hope you get it solved

[p.barg]

Unfortunately, the provider wasn't of much help so far...
He said that maybe an extension is required by PHP and not loaded by their configuation and that we should tell them
what extension that might be and they would enable it then. No idea, what that might be. In all other installations
at different providers we didn't encounter such an issue.

Anyone with any idea?