WMS service connection error in ArcGIS Portal 10.9

[NesmieianovViktor]

ArcGIS Portal runs in a enterprise environment.
Web Adapter is installed on a separate Linux container.
version 10.9

In a corporate environment, there is an additional proprietary WMS service.
If I request
https://myserver.corporateserver/wms?service=wms&request=GetCapabilities
on the browser page, I get the correct response in xml format

When I try to add a service as an Url From Internet WMS(OGC) element, I see in the console that a request is being sent

https://myarcgisportal.corporateserver/arcgis/sharing/proxy?https://corporateserver/wms?

and this request returns error 500..

What needs to be configured to be able to add WMS services to ArcGIS Portal?

[A_Wyn_Jones]

Hi @NesmieianovViktor,

Could you please ask your Portal admin to check whether the Proxy hosts have been restricted? 
https://enterprise.arcgis.com/en/portal/10.9.1/administer/windows/restricting-the-portal-s-proxy-cap...

The machine where ArcGIS Portal is running may not have a connection to your WMS endpoint - this can be checked by using the checkURL function of Portal.

The URL may need to be added to the allowedProxy list or you may find there are some connectivity issues to the URL.

Hope this helps,

A

[NesmieianovViktor · Accepted solution]

The problem was solved by installing the additional organization certificate 

arcgiswebadaptor/arcgis/portaladmin/security/sslCertificates

[Hal-AhmedShehata]

I'm trying to use ArcGIS Online with WMS and having the same error. Obviously, I can't import certificates in AGOL. Any idea what can be done?