Have you recently changed a password?

If you have changed the password at the operating system level for the user ID that is used either as the ServiceUserId or the DataSourceUserId for any of the WebSphere Message Broker components, this might cause a problem. If so, perform the following steps:

Related tasks
Troubleshooting and support
Making initial checks
Securing WebSphere MQ resources
Related reference
mqsichangebroker command
mqsichangeconfigmgr command
mqsichangeusernameserver command
mqsichangedbimgr command