Problems with Oracle Express Server 6.3.4 Installation on newer Ubuntu release

hi,

i managed to get this (at least 15 year old) system running on an ubuntu 16.04 server in an chroot environment.

now i need to migrate to a 18.04 system and did the same as last time.

when starting the express.sh script i got the error:

[28870]  01/09/2019 15:29:36  xsdaemon: [Cannot read the configuration info.]

[28870]  01/09/2019 15:29:36  xsdaemon: [Check to make sure that /home/oracle/OraHome1/olap/oes.key exists and is readable. Also check the /home/oracle/OraHome1/olap/log/xsagent.log file for oes.key related errors.]

The oes.key is exact in this folder an readable by everyone. the owner is oesdba and the passwords are set as specified in the oes.key.

There are no other hints in the xsagent.log or xsdaemon.log.

Can anyone help me?

Best regards

Thomas