Jupyterhub ssl not working with DER format cert


I try to get Jupyterhub with ssl working in our environment.
When I create a self signed cert with openssl, it runs and I can access hub with Edge browser, but only in the non secured way.
But it works.

We have trusted certs for our server in DER format which includes the keys already.
When I try to use those, Jupyterhub is not starting because of ERR_OSSL_PEM_NO_START_LINE.

I can use openssl to convert our trusted cert to PEM format.
Using that one, Jupyterhub starts, but Chrome and Edge browser tell me, that the cert is not valid or not using the right cypher.

So it looks like, that a PEM format is accepted from Jupyterhub, but not a DER format.
But with the PEM format, the browser are refusing the connection.

Kind regards

in the end I got it working:
I started to create the new key with keytool → .jks
how ever I did that, no success in the end…

then I used openssl to create a new key with csr, used that csr to get the trusted cert,
used the pem version of the cert together with the private key file
and set CONFIGPROXY_SSL_KEY_PASSPHRASE as an environment variable for the key pwd…

now it works, hub via ssl on RHEL


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