I recently had a strange issue. We had a server file system filled up because of a runaway log file. The log files were removed to free up some disk space but during this process the Progress Admin Server lost its configuration information.
I did a lot of digging and found the configuration file in c:oe102apropertiesubroker.properties where c:oe102a is the install directory of Open Edge. There is also a backup file in c:oe102apropertiesubroker.properties.old. I was able to copy the contents of this file into ubroker.properties restart the Admin Server and everything came up.
