Thumbnails not being generated Enterprise 10.6.1

[ClintonBallandis1]

Hi,

I'm having issues with thumbnails not being created in ArcGIS Enterprise 10.6.1. When I try to create a hosted layer view I get the following error

"The item you requested cannot be found. The items may have been deleted or you may have entered an incorrect url"

The thumbnail preview is also blank as per the Figure 2 below. It seems that the existing thumbnail from the source layer (Figure 1)  isn't being carried over to the hosted view or a new thumbnail can't be created for some reason. 

I also get the same error if I try and publish a hosted feature layer from pro without specifically creating a thumbnail prior to publishing.

The error stops being generated as soon as I add a thumbnail image or make a change and save the layer. It appears to that saving automatically re generates a thumbnail. 

                                                                        (Figure 1 Source Hosted layer)

                                                                          (Figure 2: Hosted Layer View)

In the chrome dev tools I'm getting the following message:  

I saw the following in the help documentation

Thumbnails for newly created web maps are not generated or do not display correctly.

You may encounter this problem if your web maps contain ArcGIS Server services that use HTTPS. If this is the case, check if the portal is configured with a print utility service from an ArcGIS Server site. The print service may be running on a machine that does not trust Certificate Authority (CA) signed certificates from the ArcGIS Server site providing the HTTPS services. Each machine running the print service will need to be configured to trust these CA certificates at the operating system level. See Enable HTTPS using a new CA-signed certificate for details on how to do this.

I'm using self signed certificates on my portal, server and datastore with a externally signed certificate on the webadaptor. I'm wondering if I need to get CA certificates add to the Portal, Server and Datastore? 

My print services works as expected in terms of generating pdfs etc. Are thumbnails also generated from the same print service?

Thanks

Clinton

[ClintonBallandis1 · Accepted solution]

Hi all,

I managed to resolve this issue. It looks like something in the thumbnail process was trying to access the service infoitems (where the thumbnails are stored) for our basemap map layers. For some reason access to the infoitems was being blocked. 

I ended up rebuilding our basemap webmaps checking that the infoitem was avaliable for each layer.

No more "The item you requested cannot be found. The items may have been deleted or you may have entered an incorrect url" errors.

Thanks,

Clinton

[LeoLadefian3]

I'm getting a similar error, it seems like the thumbnail is not being shared properly:

info/thumbnail/ago_downloaded.png' is not accessible: Error. Server returned HTTP response code: 401 for URL:

any ideas?