When trying to change the "Supported JRE Version " in the OneClick Client Configuration section, the following error appears:
Error saving to custom-jnlp-config.xml: Error on line -1: Premature end of file.
1. Out of Disk Space
2. Corrupt XML
Confirm there is enough disk space available on the host OS.
If there is, the file is likely corrupt or empty.
Recreate the file and retest.