RabbitMQ/Erlang Troubleshooting guide

[Bastien_Laugiero]

RabbitMQ is an open-source message broker software that implements the Advanced Message Queuing Protocol. The RabbitMQ server is written in the Erlang programming language. NPrinting uses RabbitMQ and Erlang and those are installed during the NPrinting installation as part of the requirement. 

RabbitMQ or Erlang may fail to install or run. 

Example symptoms: 

• Erlang cookie cannot be written
• NPrinting Scheduler cannot be started and/or NPrinting Engine show Offline in the NPrinting Web Console
• Cannot start RabbitMQ Service after fresh installation
• After server or service restart, RabbitMQ service doesn't start. 

Environment:

• Qlik NPrinting 

Resolution

1. Take a backup of your NPrinting setup. See How to BackUp and Restore Qlik NPrinting Repository Database from End to End 
2. Follow the instructions provided in Qlik NPrinting messaging service (RabbitMQ) start up and connection problems 
   Note: Verify that you have selected your NPrinting version in the Help site menu.

Cause(s)

1. Erlang cookie mismatch: the cookie files in these locations holds a hash. these hash must match. if by chance these files gets overwritten, they may not have same hash.
2. Corrupted Installation of the entire NP server perhaps due to different user service account used to installed NPrinting (resolved in Sept 2019 NPrinting and later versions. Changing service accounts with these versions. See User accounts).
3. Aggressive antivirus software: sudden crash of the Qlik NPrinting server that may have corrupted or missing NPrinting system files
4. Missing RabbitMQ users during the NPrinting server installation. Note: this issue is resolved in NPrinting June 2020 and later versions.