White screen accessing workspace

Question

I can't access my workspace since yesterday. After login, it just keeps the screen white and disconnect, maybe it's because I turned on the firewall inside the workspace, I don't know.

The log: 
"Error while making a request to : https://d1cbg795sa4g1u.cloudfront.net/prod/iad/d-906745bae9/en_US/wsassets.json. Message: HttpClient - 4xx Network error
Exception while getting file headers from URI: https://d1cbg795sa4g1u.cloudfront.net/prod/iad/d-906745bae9/en_US/wsassets.json. Exception: WorkSpacesClient.Common.Infrastructure.ExceptionHandler.WorkspacesClientNetworkException: HttpClient - 4xx Network error
 ---> System.Net.Http.HttpRequestException: Response status code does not indicate success: 403 (Forbidden)."

I hope someone can help me with it, 
Thanks.

Answer

This usually happens with PCoIP WS if UDP port 4172 is blocked. The Windows firewall by default is configured to allow communication on the ports required by the Workspaces service. If you made any changes to the Windows firewall then it can cause issue. In your case it is UDP port 4172 seems to be blocked. You can connect to the Workspace via [RDP](https://aws.amazon.com/premiumsupport/knowledge-center/connect-workspace-rdp/) and revert the changes. If you do not have RDP access then you may have to [rebuild the Workspace](https://docs.aws.amazon.com/workspaces/latest/adminguide/rebuild-workspace.html).

White screen accessing workspace

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