Self Signed SSL Certificate M Files

Have you seen this document?

Setting Up M-Files to Use gRPC (site.com)

Hello Craig Thank you for guidance,

i  take the self-signed option and i generated a certificate but when i add this certificate i got the error:

The only difference to purchased certificates is that you have to distribute the self-signed certificates to the client. :-)

This isn't something that I have any personal experience on, unfortunately.  I would cross-reference the document and make sure that the certificate you're creating is of the correct format (PEM with base64 encoding or PKCS#1 format).

Maybe someone else here can guide you, or perhaps reach out to your partner to see whether they have some advice.