[webmin-l] webmin gui certificate upload - Failed to save new key : Missing or invalid PEM format key

[ѽ҉ᶬḳ℠ <vt...@gm...>]

Ubuntu Linux 18.04
Webmin  1.881
Authentic Theme 19.19

Upload of 4096 bit / sha512WithRSAEncryption / X509v3 extensions
certificates via Webmin gui fails with -> Failed to save new key :
Missing or invalid PEM format key.
Pasting the cert/key text produced the same outcome.

Certificates/keys are tested various ways with no issues and appear to
be ok/working otherwise.

Looked into the following but could not find an option to set the
cert/key path manually and check whether it would perhaps work that way
and if is a bug in the gui eventually:

"/etc/webmin/webmin/config"
"/etc/webmin/config"
"/etc/webmin/miniserv.conf"

Where can I point Webmin outside the gui to the certifcates/keys?