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Advanced troubleshooting of the GRPC and or CEF Error Issues

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Digital Support

Advanced troubleshooting of the GRPC and or CEF Error Issues

This article lists the resolution and troubleshooting steps that must be followed if images are not rendered correctly in NPrinting reports.





Troubleshooting Steps:

Image import failures may be due to some configuration errors. The following must be checked:

  • Assistance/suggestions mode for the Qlik Sense charts is not supported. Be sure that it is disabled for all the objects imported in the report.
  • The imported object must be a native Sense object or a supported 3rd party extension and configured correctly as per specification (see "References" section)
  • Certain Qlik Sense visualizations from the visualization bundle are not supportedSee compatibility matrix here:
     Creating a visualization using a custom object
  • For a listing of compatible, built-in Qlik Sense objects, check the compatibility matrix found in the following link to better understand specific Qlik Sense object limitations with NPrinting reporting. 
    Working with Qlik objects
  • Please check and validate minimum cipher requirements on the NPrinting and Qlik Sense server. See
  • Check that the internet options/proxy settings are cleared as per article:
    NPrinting Issues to generate report and previews, connect to Qlik Sense apps, image and objects issu...
  • Check that NPrinting Engine and Server Internet Options are configured. See:
    How to Configure NPrinting Server and NPrinting Engine computer Internet Options
  • Check that 'In' and 'Out' bound ports between the NPrinting server NPrinting engine and the Qlik Sense server are configured. Keep in mind that Ports 4997 and 443 must now also be configured since November 2018 release of NPrinting.
  • Check that ports 2727 and 15672 are not being used by any other process/program on the NPrinting server and engine computers. These ports are required for normal NPrinting operation. See Ports - Qlik NPrinting
  • Check that the Qlik Sense objects and or Qlik Sense visualization used in your NPrinting report are supported as per the "Keep in Mind" section above
  • Check if HTTP is used in the Proxy field of the NPrinting Connection to the Qlik Sense app in the 'Proxy Address' field. If yes, see article
    NPrinting Unexpected CEF rendering exception with HTTP connection
    otherwise continue to the next points below


Resolution steps:

Resolution 1 - Fully Qualified Domain Name path or some other parameter of the original Qlik Sense server certificates may have changed. Use the following article to resolve this issue:

! To ensure editing the correct file, please do the following before proceeding as directed below:
  • Open windows File Explorer
  • Click 'View' tab
  • In 'Show/Hide' area of the 'View' ribbon, Click checkbox "File Name Extensions" in order to show the full file name


Resolution 2 - GRPC error: Check NP CEF Engine log file: May be represented by the error: "The remote server returned an error: (401) Unauthorized" .
(Internal JIRA defect reference: OP-8814)

  • Check that the path to the QMC proxy is the same as the connection path used in the NP connection proxy address path.
  • You must also ensure that port 443 and port 4997 are not blocked in your environment as mentioned in the article description.

Resolution 3 - If the NPrinting Error logging or preview errors contain the message "CEF rendering exception - "Buffer cannot be Null" go to the following article for the solution: 


Resolution 4 - If Resolution 1 and 2 above do not resolve the issue and all image export requirements are met, check and perform the steps below:

  • Stop the NPrinting Engine Service.
  • Open the renderer.config file in C:\Program Files\NPrintingServer\NPrinting\Scheduler. You may need to open the file in administrator mode.
  • Make a backup copy of the file.
  • Add (or modify if present) the following parameter:
    <add key="webrenderer-timeout-sec" value="120" />
    120 is the time in seconds for the timeout. It can be increased further if necessary.
  • Restart the NPrinting Engine service

Increasing these timeout values may lead to improved performance as NPrinting may simply need more time to execute tasks and report generation.


How to Enable 'Tracing'

If resolutions above have not resolved the issue, please perform the following steps and reproduce the issue one again in order to retrieve additional tracing information necessary for a deeper investigation. Then zip and upload the requested folder below up to the support case. 



Possible causes of GRPC error

  • assistance/suggestions mode is enabled (it is currently on the road map to have this feature fully supported)
  • the chart is an unsupported 3rd party extension (map extensions for example). See article below regarding Qlik Sense extensions and how to enable them for image export.
  • In some cases, image web rendering default time while connected to Qlik Sense needs to be adjusted perhaps due to network latency or other network performance related issues
  • Communication between the NPrinting server and the Qlik Sense server is discovered to be problematic.
  • The Qlik Sense server itself could be overloaded and not responding to the NPrinting server in a timely manner.
  • When NPrinting is used in conjunction with Qlik Sense Deployments From September 2018 and higher where "HTTP" is used rather than "HTTPS", specific CEF or GRPC errors will be logged. See article Qlik NPrinting Unexpected CEF rendering exception with HTTP connection for more information.
  • Certificate mismatch as identified in article NPrinting Verification process does not capture certificate FQDN mismatch in turn resulting in GRPC ...
  • Invalid path used in the NP connection 'proxy' address path. Path used with the NP connection should be the same as the path used to open the QMC or QS Hub
  • Error logging to look for NPrinting Logs: "Failed to open a resolver for connection" and "The remote server returned an error: (403) Forbidden"


Version history
Last update:
‎2022-08-26 05:33 AM
Updated by: