On some HP printers, when I try to import a certificate to enable HTTPS for the printer's Embedded Web Server (EWS), I get the error message "The format of the file is invalid". This happens both (1) when I have created the CSR using openssl and (2) when I use the "Create a Certificate Request" option in EWS.

Updating to the latest firmware does not help.

Example model: HP Color LaserJet MFP M477fnw

Embedded Web Server  Networking tab, Certificates pane showing error message "The format of the file is invalid"

1 Answer 1


This failure occurs when the certificate file includes the full certificate chain to the root certificate. Apparently, the affected printers cannot process a chain of root and intermediate certificates.

When you submit your certificate signing request (CSR) to your certificate authority (CA), whether that be internal PKI or a commercial CA, request that it omit the certificate chain from the certificate. Then the printer will be able to successfully import it.

I suspect that it might be possible to remove the certificate chain using a tool like openssl (so you wouldn't have to make a special request to your CA), but that is beyond my expertise.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.