OH2.2 MQTT binding can't be used after changing password for Mosquitto broker

[binderth (Thomas Binder)]

first things first:

• to my knowledge, openHAB needs the password stored in mqtt.cfg, there’s currently no way to use a passwd-file
• of course you can use a broker configuration without authentification (and openHAB can use that broker also)

with changing all that mqtt-configuration on-the-fly you almost certainly ran into a bug, please have a look here:

Clear the Cache

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. Installed OH If you are running an installed OH (openHABian, installed using apt or yum): openhab-cli stop openhab-cl…

if clearing /var/lib/openhab2/cache and /var/lib/openhab2/tmp won’t work, you should have a look in
/var/lib/openhab2/config/org/openhab/mqtt.config it should contain the same info (e.g. no credentials), if not, do as in the “Clear the Cache”-thread described and stop OH2, delete cache and tmp again but plus delete mqtt.config (or change accordingly), then start OH2 again