ArcGIS Enterprise: Unable to accept the invitation response. Collaboration cannot be established

Error Message

When attempting to import the invitation response of a distributed collaboration between the ArcGIS Enterprise portal and ArcGIS Online, the process fails and returns the following error message:

Error:
Unable to accept the invitation response. Neither the host nor the guest can reach each other so a collaboration cannot be established.

Cause

• Network traffic from the portal machine passes through the firewall, which blocks traffic to the ArcGIS Online domains.
• The network configuration requires all external traffic to be routed through a forward proxy server for the ArcGIS Enterprise portal. This setup ensures compliance with security policies that mandate monitoring and controlling access to external resources.

Solution or Workaround

Depending on the cause, the workarounds provided are applicable.

Configure the firewall's allow list to access the ArcGIS Online domains

Note:
The following solution may require the assistance of a network administrator and the organization's IT department.

Configure the firewall of the network or machine with ArcGIS Online to allow the following domains:

• https://ago-item-storage.s3.amazonaws.com
• https://ago-item-storage.s3.us-east-1.amazonaws.com
• https://*.arcgis.com
• https://*.arcgisonline.com
• https://*.esri.com
• https://*.blob.core.windows.net

Refer to PDF: Domain Requirements for ArcGIS Online for additional information.

Note:
Note that users must be signed in with an organizational account to view the document, as it is located in the secure document section of the ArcGIS Trust Center.

Configure the ArcGIS Enterprise portal with a forward proxy server

Configure the ArcGIS Enterprise portal to use a forward proxy server. Refer to Portal for ArcGIS: Configure your portal to use a forward proxy server for instructions and more information.