I recently upgraded my system and found my previously well-working dosemu stoped working giving me the same error message.
Durring the update, the install of dosemu-freedos complained about /usr/share/dosemu/drive_z not being a file, but a directory and stoped the update process.
So i renamed the existing directory /usr/share/dosemu/drive_z to something like /usr/share/dosemu/drive_z_old and restarted the update process.
This time dosemu_freedos updated without errors.
Anyway runing dosemu in the console gave me the error mesage you recevied.
Remembering the install complained about drive_z i checked /usr/share/dosemu/drive_z only to find out it was a file.
Checking the contents of the file revealed it looked like a sample of autoexec.bat .
Doing a rpm -qilv dosemu i noticed something weird : /etc/drives/c and /etc/drives/d were links to some files on /home/some_other_nonexisting_user/.
So i simply deleted /etc/drives/c and /etc/drives/d , renamed the file /usr/share/dosemu/drive_z to something else, renamed /usr/share/dosemu/drive_z_old from my previous install back to /usr/share/dosemu/drive_z and recreated the files /etc/drives/c and /etc/drives/d as links to /usr/share/dosemu/drive_z.
Afterwards, runing dosemu in console, everything went well.
The programs i usualy run in dos-emulation mode performed without errors.
I hope this is usefull to you.