Advanced troubleshooting of the GRPC and or CEF Errors in Qlik NPrinting

Andre_Sostizzo — Thu, 02 May 2024 15:12:42 GMT

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

NOTE: Before proceeding below, please check this article

NPrinting Qlik Sense Images Fail to Render Export Generate or Preview

Troubleshooting Steps:

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

Insufficient system resources: Low Qlik Sense, QlikView and NPrinting System resources can cause this issue. Please do performance monitoring to check for Peak CPU and RAM usage that on all NP QS and QV servers. NPrinting has the ability to exhaust a production Qlik Sense or Qlikview server if those servers are not sufficiently provisioned with enough RAM in particular. https://community.qlik.com/t5/Official-Support-Articles/Finetuning-and-preparing-your-NPrinting-202x-Deployment-for-use/ta-p/1716222
- It may be useful to Enable performance logging on the NP, QS and or QV servers to verify if it is being heavily taxed while NPrinting reports and or report publish tasks etc are being executed. Qlik Sense - How to monitor resources using Microsoft Performance Monitor

Assistance/suggestions mode for the Qlik Sense charts is not supported. Ensure it is disabled for all the objects imported in the report.

The imported object ideally will be a native Qlik Sense chart object. 3rd party extensions may result in unexpected results. Contact your extensions vendor for 3rd party extension support

Certain Qlik Sense visualizations from the visualization bundle are not supported: See 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 Qlik NPrinting and Qlik Sense server. See NPRINTING ERROR CEF RENDERING EXCEPTION Cipher Issue

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 issues and on demand issues

Check that Qlik 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 Qlik NPrinting server Qlik 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 Qlik 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 Qlik NPrinting Connection to the Qlik Sense app in the 'Proxy Address' field. If yes, see article
NPrinting Unexpected CEF rendering exception with HTTP connection

Check that the Qlik Sense Proxy default 'https://' listening port settings has not been changed. Open the following link for more information:
NPrinting Designer CEF Rendering error and or Error Object reference not set to an instance

Check for the use of a Qlik Sense proxy 'prefix' in the Qlik Sense Management Console. If one exists, via the NP web console, the prefix must be added to the NP connection string ie: https://qlikserver1.qlik.com/qlik

Check to see if anything has been entered into Additional Response Headers under the Qlik Sense Virtual Proxy being used (select Advanced to view), if so remove and test.

Check the Qlik NPrinting logs for 'Websocket' errors. If found check this article to resolve that issue.
NPrinting Engine connection stays offline on February 2019 release and newer - RabbitMQ log shows "Insufficient Security no_suitable_ciphers"

Abort all running Task and On Demand Task executions then reboot the Qlik NPrinting Server, Qlik NPrinting Engine computer and the Qlik Sense server at the first available opportunity and retest if the issue still persists. Ensure all services on each computer are up and running before retesting.

If the issue persists after checking all points above, please check the solutions in the resolutions section of this article.

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: NPrinting Verification process does not capture certificate FQDN mismatch in turn resulting in GRPC errors

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: CEF rendering exception - "Buffer cannot be Null" Error in NP report preview with Qlik Sense Connection"

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 up to 300 if necessary and retest.
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. These changes also need to be made after an NPrinting upgrade. NP Config files are overwritten during the upgrade process.

How to Enable 'Logging'

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

Enable debug logging as per Troubleshooting logs - Qlik NPrinting

Causes:

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 errors
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"

Reference:

Creating visualizations using chart suggestions
Enabling export of your visualization extension
Using Qlik Sense third-party extensions

article Advanced troubleshooting of the GRPC and or CEF Errors in Qlik NPrinting in Official Support Articles