After installing a new UF, why is it not forwarding logs to the Indexers?

[u2s1e0n2]

05-10-2018 15:13:13.954 +0000 ERROR TcpOutputProc - Error initializing SSL context - invalid sslCertPath for server 45.125.XXX.X:9997
05-10-2018 15:13:13.959 +0000 ERROR SSLCommon - Can't read key file /opt/splunkforwarder/etc/auth/server.pem errno=151429224 error:0906A068:PEM routines:PEM_do_header:bad password read.

I just installed a new UF but it's not forwarding logs to the Indexers and the $SPLUNKHOME /var/log/splunk/splunkd.log shows the error message above. The IP in the error message is that of the Indexer: It is connecting to the Deployment Server and getting configs but not sending logs to the Indexers.
I need help understanding what is happening. I have reinstalled the UF but still got the same error messages.

The certs are default Splunk certs

Thanks

[xpac]

Please check if /opt/splunkforwarder/etc/auth/server.pem exists and can be read by the user Splunk runs at it. Have you modified it, or the password used for it? Does your outputs.conf contain a special sslCertPath settings for your indexers? If yes, check that file too.