ssl problem getting key 'private.key' 335544427: error:1400006B:UI routines::processing error

[qlands]

I am getting this error with a new set of certificate files that we installed in our Apache2 server.

The certificate files work well with Apache2 but not with mosquitto. The log is:

1695194754: Compiled with OpenSSL support
1695194754: Doing SSL library init
1695194754: canonical_hostname = b9b41a085ca0
1695194754: _realloc: size 776: create vhost
1695194754: _realloc: size 80: vh paths
1695194754: _realloc: size 224: vhost-specific plugin table
1695194754: _realloc: size 72: same vh list
1695194754: Creating Vhost 'default' port 9001, 3 protocols, IPv6 on
1695194754: Vhost 'default' using TLS mode
1695194754: SSL options 0x2520000
1695194754: ssl problem getting key '/etc/mosquitto/conf.d/ssl/private.key' 335544427: error:1400006B:UI routines::processing error
1695194754: lws_create_vhost: lws_context_init_server_ssl failed

The websocket conf file is:

listener 9001
protocol websockets
cafile /etc/mosquitto/conf.d/ssl/ca_bundle.crt
keyfile /etc/mosquitto/conf.d/ssl/private.key
certfile /etc/mosquitto/conf.d/ssl/certificate.crt

The certificates where generated using TLS 1.3.

The weird thing is that the same files work in Apache and previous files worked fine but not with the new files.