topic Re: Image Preview Error - CEF Rendering Exception in Qlik NPrinting

Image Preview Error - CEF Rendering Exception

WMLouis — Fri, 12 Feb 2021 19:06:06 GMT

When attempting to generate images we are getting the following error:

the preview request failed with message: object 'xxx' from sense app 'xxx' had problems when rendering. Error cef. rendering exception. error during GRPC request. error: engine.Navigator.QlikSense.sdk.rendering.mashuploadexception: request with id 'xxx' failed with remote error errorloadurltimeoutresult, mashup failure

We're on the April 2020 version of Qlik Sense and Nprinting.

Running the Benchmarks resulted in error:

System.Exception: Object <objectID> of Sense app <appID> failed to render. Error Buffer cannot be null

The Benchmarks error log records it as:

2021-02-12 13:03:37,117 [11] ERROR Engine.Navigator.QlikSense.SDK.Extensions.SdkExtensionMethods - Engine.Navigator.QlikSense.SDK 18.40.0.0 Engine.Navigator.QlikSense.SDK.Extensions.SdkExtensionMethods 20210212T130337.117-05:00 ERROR <RedactedServerNameHere> 0 0 0 0 0 0 0 0 ERROR: System.ArgumentNullException: Buffer cannot be null.??Parameter name: buffer?? at System.IO.MemoryStream..ctor(Byte[] buffer, Boolean writable)?? at Engine.Navigator.QlikSense.SDK.Extensions.SdkExtensionMethods.ExportToImage(IGenericObject sheetObject, SenseApp app, Guid requestId, Dictionary`2 propertyValues, Int32 width, Int32 height, Int32 dpi, Double zoom, KeepAspectRatioStrategy keepAspectRatioStrategy, FallbackStrategy fallbackStrategy)

I think I've tried everything.

I've extended the timeouts, checked and reinstalled certificates, setup https. Any help would be greatly appreciated. I'm not sure whatelse to try.

Re: Image Preview Error - CEF Rendering Exception

Frank_S — Sat, 13 Feb 2021 00:02:43 GMT

Hi @WMLouis

It's not clear which certificates you are referring to. Also did you recently upgrade to April 2020 Qlik Sense.

If so, please check the following article to ensure you have exported your certificates accurately from Qlik Sense and copied to the expected folder on the NP server.

https://community.qlik.com/t5/Support-Knowledge-Base/NPrinting-Qlik-Sense-Images-Fail-to-Render-Export-Generate-or/ta-p/1713381

Kind regards...

Re: Image Preview Error - CEF Rendering Exception

WMLouis — Tue, 16 Feb 2021 18:56:22 GMT

@Frank_S

The certificate I was referring to were the Qlik Sense ones.

I've since updated the Nprinting server to November 2020 and run into what feels like the same error.

I think I may have found a smoking gun in the "nprinting_engine_cef" log.

It reads:

trying to get login cookie via a qlikTicket from:https://redacted-Sense-server-name/hub/?qlikTicket=K5nPX3FrQsTjmEpk
No cookie found for domain https://redacted-Sense-server-name/. Check that your virtual proxy allows NTLM authentication
An issue occurred in MashupServer.GetAuthenticationCookiesAndConsumeQlikTicket. Proceeding anyway by using Windows authentication to load the mashup page. ERROR: System.InvalidOperationException: No cookie found for domain https://redacted-Sense-server-name/. Check that your virtual proxy allows NTLM authentication↓↓ at Engine.Navigator.QlikSense.SDK.Rendering.SenseAuthenticator.GetAuthenticationCookiesAndConsumeQlikTicket()↓↓ at Engine.Navigator.QlikSense.SDK.Rendering.SenseAuthenticator.RefreshAuthCookies()

Do you know what this means? Do I have to setup a proxy in Sense?

I've also gotten this from the Benchmarks err.log

ERROR: System.ArgumentNullException: Buffer cannot be null.??Parameter name: buffer?? at System.IO.MemoryStream..ctor(Byte[] buffer, Boolean writable)?? at Engine.Navigator.QlikSense.SDK.Extensions.SdkExtensionMethods.ExportToImage(IGenericObject sheetObject, SenseApp app, Guid requestId, Dictionary`2 propertyValues, Int32 width, Int32 height, Int32 dpi, Double zoom, KeepAspectRatioStrategy keepAspectRatioStrategy, FallbackStrategy fallbackStrategy)

Thank you

Re: Image Preview Error - CEF Rendering Exception

Frank_S — Tue, 16 Feb 2021 19:17:14 GMT

@WMLouis

Yes if you are connecting directly to a proxy node that is not linked to a virtual proxy, this could be the issue. Further, NPrinting only support NTLM authentication, head and saml auth for example, are not supported authentication methods.

https://help.qlik.com/en-US/nprinting/February2021/Content/NPrinting/DeployingQVNprinting/NPrinting-with-Sense.htm#Requirem

Microsoft Windows NTML authentication on the Qlik Sense proxy. SAML and JWT are not supported. If your virtual proxy uses SAML or JWT authentication, you need to add a new virtual proxy with NTLM enabled for Qlik NPrinting connections.

The following must be correctly set up:

A Qlik Sense proxy.
A Qlik Sense virtual proxy.
A link between the proxy and virtual proxy.
The Qlik Sense virtual proxy must be reachable from the Qlik NPrinting Engine machines to retrieve data to create reports. It must be reachable from the Qlik NPrinting Server to publish to the Qlik Sense hub.

In your case I suspect you 'may' need to set up Virtual Proxy that uses windows authentication (ticketing, windows) then link your proxy node to the new virtual proxy via the virtual proxy settings.

If all the requirements have been met and your QS client.pfx cert has been exported correctly and copied to C:\Program Files\NPrintingServer\Settings\SenseCertificates folder on the NP server, then we may need to have a closer look at your environment to investigate more thoroughly. If so, please start a support request with the Qlik Support desk at your convenience.

Kind regards...

Re: Image Preview Error - CEF Rendering Exception

WMLouis — Tue, 16 Feb 2021 22:19:18 GMT

Setting up a Virtual Proxy connection in Sense and added the prefix to the url fixed my issue. Thank you so much!

Re: Image Preview Error - CEF Rendering Exception

Frank_S — Tue, 16 Feb 2021 23:04:58 GMT

No worries @WMLouis!

Glad to help...fs