Qlik NPrinting Engine Logs Show Precondition Failed errors

[Frank_S]

Qlik NPrinting shows diminished performance with two or more active Qlik NPrinting Engines. 

The Qlik NPrinting RabbitMQ logs print Precondition Failed errors.

Diagnosis

1. Navigate to the RabbitMQ and Qlik NPrinting logs folders:
            C:\ProgramData\nprinting\RabbitMQ\log
            C:\ProgramData\nprinting\logs
2. Download a copy of the above logs and review them for Precondition Failed errors.

Environment

• Qlik NPrinting
• One or multiple Engines are installed

Resolution

1. Take a backup of the Qlik NPrinting database
   1. How to BackUp and Restore Qlik NPrinting Repositor... - Qlik Community - 1715863
2. Uninstall Each and Every  Qlik NPrinting Engine connected to your Qlik NPrinting Server
3. Uninstall the Qlik NPrinting Server
4. Install Qlik NPrinting Server - This will recreate all queues in the correct way. Make sure to apply your Product Key or Signed License Key before proceeding to the next step
5. Install Qlik NPrinting Engine or Engines s using the same version as the Qlik NPrinting server version
6. Restore the Qlik NPrinting Database
7. Verify if the Qlik NPrinting Product license is applied. If not, reapply it. 
8. Open the Engine Manager and verify that the Qlik NPrinting Engines are online
9. Open any connection and verify the connection to ensure both or multiple engines are verifying normally.

Cause 

• Upgrading Qlik NPrinting Server while running with an incorrect/incompatible Qlik NPrinting Engine version
• Failed to stop the NPrinting Engine service before beginning the upgrade process
• Failed to upgrade the NPrinting Engine service to match the upgraded NPrinting server

Example of invalid configuration. At any time during the upgrade process

• NPrinting server version May 2022 SR 3 running concurrently with NPrinting Engine version May 2022 SR 2
• Upgrading the NPrinting Server with a newer version (May 2022 SR 3 for example) but leaving your NPrinting Engine(s) May 2022 SR 2 for example) running for any period of time during the upgrade process

This will result in incompatible scheduler queues executing which results in a race condition.

The result is that there is a noticeable report execution performance degrade.

Mitigation/Prevention of this issue

• During the upgrade process, it is required to stop all services including all NP engines on the same or different Servers. (See https://help.qlik.com/en-US/nprinting/Content/NPrinting/DeployingQVNprinting/Upgrading-Qlik-NP...
  • Open Windows Services.
  • Stop the following Qlik NPrinting services by right-clicking them, and then clicking Stop:
    • Qlik NPrinting Engine
    • Qlik NPrinting Scheduler
    • Qlik NPrinting WebEngine
    • Qlik NPrinting MessagingService
    • Qlik NPrinting RepoService
    • Qlik NPrinting License Service
• The NPrinting Server and NPrinting Engine MUST be the same version: (See https://help.qlik.com/en-US/nprinting/Content/NPrinting/DeployingQVNprinting/Qlik-NPrinting-installa...
  • When you install or upgrade your Qlik NPrinting Server, Qlik NPrinting Engines, and Qlik NPrinting Designer, ensure that they are all the same software version. Mixing versions of Qlik NPrinting components is not supported.

Related Content

• Qlik NPrinting Installation
• Qlik NPrinting Upgrading