When setting up AzureVirtualDesktop the error
{"code":"DeploymentFailed","message":"At least one resource deployment operation failed. Please list deployment operations for details. Please see https://aka.ms/arm-deployment-operations for usage details.","details":[{"code":"VMExtensionProvisioningError","message":"VM has reported a failure when processing extension 'Microsoft.Compute.CustomScriptExtension'. Error message: "Failed to download all specified files. Exiting. Error Message: CustomScript failed to download the blob fileUri_{2} because it does not exist. Please create the blob and try again, the response code and message returned were: "The remote server returned an error: (404) Not Found. The specified blob does not exist." (Service request ID = 8d5c959a-301e-0004-66cd-a312ea000000)"\r\n\r\nMore information on troubleshooting is available at https://aka.ms/VMExtensionCSEWindowsTroubleshoot "},{"code":"VMExtensionProvisioningError","message":"VM has reported a failure when processing extension 'Microsoft.Compute.CustomScriptExtension'. Error message: "Failed to download all specified files. Exiting. Error Message: CustomScript failed to download the blob fileUri_{2} because it does not exist. Please create the blob and try again, the response code and message returned were: "The remote server returned an error: (404) Not Found. The specified blob does not exist." (Service request ID = d6225d60-e01e-0081-54cd-a33f37000000)"\r\n\r\nMore information on troubleshooting is available at https://aka.ms/VMExtensionCSEWindowsTroubleshoot "}]}
is given. When looking at the template provided by Azure it seems the custom script extension field is automatically added. It seems this is done on the Azure side, and can not be edited even with escalated permissions within the Azure environment.