azure front door - why failover not working

Azure Front Door configurations:

one backend pool;
two backends (both are azure app service) in the pool;
Probe interval: 30 seconds
Load balancing: Sample size - 2; Successful samples required: 1; Latency sensitivity: 0
one of backend is stopped;

Issue:

when accessing the front-door (my-afd-url.azurefd.net), it returns 403 occasionally. from my understanding, if any backend is unhealthy , front-door should always direct requests to the healthy one.

it seems failover not working for me. does the probe/load-balancing configuration matter here? please help.

Solution

your load balance configuration is working fine, i think error is coming from one of your servers, that is not properly configured. please check your configurations