Often when one encounters a problem with OH, particularly after an update, OH will refuse to run or certain parts of OH stop working. Some reported errors include:
- 500 or 404 errors when accessing the UIs
- lots of exceptions from Jetty or other core components in openhab.log
- OH refuses to start at all
The first step in debugging the problem is to clear the tmp and cache.
If you are running an installed OH (openHABian, installed using apt or yum):
Watch openhablog for errors, test if the problems persist. If so, serach the forum and post a new thread if you do not find a solution. To get more information in openhab.log, use
openhab-cli start --debugto enable debug logging.
Manual OH Install / Docker
Stop OH if it is running.
Delete the /var/lib/openhab2/cache and /var/lib/openhab2/tmp folders. For manual installations these folders are in your OH home folder under userdata.
Watch openhab.log for errors, test if the problems persist. If so, search the forum and post a new thread if you do not find a solution. Log into the karaf console and enable debug logging to get more information about the errors.
EDIT: Reworked to use openhab-cli for installed OH and to delete the cache and tmp folders, not just their contents.