Azure Slot Swap Job Processor failed: Cannot swap slots for site because the worker process in slot aborted the warmup request

Question

Suddenly started happening consistently across all Azure App Services using Deployment Slots.

Error Message: "Failed swapping site. Error: Cannot swap slots for site because the worker process in slot aborted the warmup request. This may happen if site has IP Restriction or URL rewrite rules that block HTTP requests."

Couldn't find any references regarding this issue, not sure if anyone else is experiencing this. Have attempted all suggested solutions in this post https://ruslany.net/2017/11/most-common-deployment-slot-swap-failures-and-how-to-fix-them/ but doesn't resolve my issue.

Nothing was done on Azure Global Configuration scope, and certainly cannot be an issue caused by any single project because this is happening across all projects deployed to Azure App Service using Deployment Slots.


Error Resonse:

{
    "caller": "SlotSwapJobProcessor",
    "channels": "Operation",
    "claims": {
        "http://schemas.xmlsoap.org/ws/2005/05/identity/claims/spn": "SlotSwapJobProcessor"
    },
    "correlationId": "xxx",
    "description": "Failed swapping site. Error: Cannot swap slots for site 'xxx' because the worker process in 'staging' slot aborted the warmup request.  This may happen if site has IP Restriction or URL rewrite rules that block HTTP requests.",
    "eventDataId": "xxx",
    "eventName": {
        "value": "SwapWebSiteTrace",
        "localizedValue": "SwapWebSiteTrace"
    },
    "category": {
        "value": "Administrative",
        "localizedValue": "Administrative"
    },
    "eventTimestamp": "2021-04-01T19:44:55.0130397Z",
    "id": "/subscriptions/xxx/resourcegroups/xxx/providers/microsoft.web/sites/xxx/slots/staging/events/xxx/ticks/xxx",
    "level": "Error",
    "operationId": "xxx",
    "operationName": {
        "value": "Microsoft.Web/sites/slots/SlotSwap/action",
        "localizedValue": "Microsoft.Web/sites/slots/SlotSwap/action"
    },
    "resourceGroupName": "defaul",
    "resourceProviderName": {
        "value": "Microsoft.Web",
        "localizedValue": "Azure Web Sites"
    },
    "resourceType": {
        "value": "microsoft.web/sites/slots",
        "localizedValue": "microsoft.web/sites/slots"
    },
    "resourceId": "/subscriptions/xxx/resourcegroups/xxx/providers/microsoft.web/sites/xxx/slots/staging",
    "status": {
        "value": "Failed",
        "localizedValue": "Failed"
    },
    "subStatus": {
        "value": "",
        "localizedValue": ""
    },
    "submissionTimestamp": "2021-04-01T19:45:04.7469589Z",
    "subscriptionId": "xxx",
    "tenantId": "",
    "properties": {
        "Message": "Failed swapping site. Error: Cannot swap slots for site 'xxx' because the worker process in 'staging' slot aborted the warmup request.  This may happen if site has IP Restriction or URL rewrite rules that block HTTP requests."
    },
    "relatedEvents": []
}

Answer 1

There could be much simpler solution - staging slot don't have any function deployed, in this case Azure throw the same error message. (Just lost several hours to figure it out, hope it will save somebody else time. :D)