After updating from stable 2.4.0 to latest snapshot (2.5) all my habmin charts disappeared. In the habmin ui I get “Error reading dashboard list” and “%%KEY ERROR%%” popups.
Creating a new chart and saving results in “Error saving …”.
How can I fix that? I wouldn’t mind losing existing charts but being able to create new ones would be nice.
The bruteforce approach was to remove all files from
/var/lib/openhab2/habmin/
Now it works again. Although all charts lost 
Too early for success. When reloading habmin the chart created disappears again, although save was successful.
Confirm on 2.5.8 Windows version.
Removing habmin/charts.xml allow to save chart, but it fails to load next time showing %%KEY ERROR%% message. When file exists - not able to save another chart.