User-460007017 posted
Hi Youssuph,
503 error is generated by WAS's failing to create worker process when handling the incoming request.
First of all, please check whether application pool has stopped working. Try to start it again. If it doesn't work. Please check the event log to find the error message, it could provide the detailed error message about how to fix this problem.
Please make sure your windows process activation service and world wide web publish service is running.
This link provide the steps to troubleshooting 503 error:
http://mvolo.com/where-did-my-iis7-server-go-troubleshooting-503-quotservice-unavailablequot-errors/
You could also enable failed request tracing to capture the detailed error log:
https://www.iis.net/learn/troubleshoot/using-failed-request-tracing/troubleshooting-failed-requests-using-tracing-in-iis
This link also provide multiple solution to resolve 503 error:
http://stackoverflow.com/questions/13322937/http-error-503-the-service-is-unavailable
Best Regards,
Yuk Ding
