Diagnostics Mode

HiveMQ comes with a so called Diagnostics Mode which will collect data about the system HiveMQ is installed to. This provides valuable information for our support team for resolving issues on the concrete HiveMQ installation.

The diagnostic mode is disabled by default and should only be enabled in case you are facing an issue with your installation. Performance will decrease and HiveMQ will write lots of information to disk, so this mode is not meant to be used in production.

Enabling Diagnostics Mode

In order to enable the diagnostics mode, modify the run.sh file for Linux systems or the run.bat file for Windows systems and uncomment the following line(s):

Enabling diagnostics mode for Linux
# Uncomment for enabling Diagnostic Mode
JAVA_OPTS="$JAVA_OPTS -DdiagnosticMode=true"
Enabling diagnostics mode for Windows
rem Uncomment for enabling diagnostic mode
set "JAVA_OPTS=-DdiagnosticMode=true %JAVA_OPTS%"

When configured correctly, HiveMQ will log a statement similar to this:

2018-07-01 12:59:25,669 INFO  - Starting with Diagnostic mode

Sending diagnostics file to the HiveMQ support team

After starting with diagnostics mode, HiveMQ will create a folder called diagnostics. All diagnostic information is located here. The following files are created:

File Name Description


Diagnostic information about HiveMQ and the system HiveMQ is running on


A trace log of HiveMQ

Run the diagnostic mode as long as you need to reproduce the issue you want to have solved. After that, stop HiveMQ. Review the created files if you’re comfortable with the information included, edit if you feel something is too sensible for our support team. Now send all files in the diagnostics folder to support@hivemq.com and describe your problem as specific as possible.

When running in diagnostic mode for some time, the log file will get huge. So be sure to run in diagnostic mode only as long as you need to demonstrate the issue you’re facing.