"Program preferences are invalid" warning

Software Rapid Photo Downloader
1

Starting RPD 0.9.33 and I’m getting a warning that says:
Program preferences are invalid
These preferences are not well formed:

Then an OK button. There aren’t any preferences listed after the colon to indicate which preferences are causing the warning. I reset the preferences to default, but I’m still getting this warning. Any advice would be appreciated. Thank you!

2

This problem may indicate a quite serious underlying problem that might be independent of Rapid Photo Downloader — it is impossible to say without knowing more. I suggest using the “Report a Problem” feature from the hamburger menu, and ensure you are failing your bug report at GitHub, not the legacy Launchpad site.