The "503 Service Unavailable" message typically appears when the application pool is in a stopped state. But why would an application pool be stopped, especially when it should be running to support website usage? Surprisingly, it’s IIS that stops it. Sounds strange? It might at first, but there’s a reason behind this.
The service is unavailable occurs if the Application Pool of the corresponding Wep Application is Stopped or Disabled or Paused. or The given user Identity of Application Pool may be invalid due to expired password or locked.
If yes, identify the associated Role/Service and install it on server. In this case " WebDAV Publishing " IIS Module. Please find below screen shot for your reference. Note: Depending on server configuration, there may be different DLLs causing this problem one by one. Other "failed to load DLL" errors for your reference.
The service is unavailable. HTTP Error 503 is another very common error that you may encounter while using a website hosted by IIS, the main reason for this error is that the application pool is stopped or disabled.
Such 503 errors were encountered on our side on Windows Server 2019 while setting up a fresh new Classic ASP website. In fact, in the App Pool, setting ".NET CLR Version " to " No Managed code " caused the App Pool to stops 2 seconds after being started, thus generating WAS 5002 and 5021 errors in the Windows Event Log.
A 503 Service Unavailable Error is an HTTP response status code indicating that your web server operates properly, but it can't temporarily handle the request at the moment.
I had a similar issue getting "503 “Service Unavailable”" over HTTPS, HTTP when I checked the console in Firefox. Everything looked fine on the IIS side: SSL certificate, ports, site running, etc.
At the company I work at we use an SSRS Report Server to publish financial reports and such. It always worked really well, but a couple of days ago, the server where the Report Server is running on...
Did you change the account it runs under through the Configuration Wizard, or through the Windows Server Services screen? In Configuration Manager, it will prompt you to back up the key used to encrypt secure SSRS content. This can cause report service to throw 503 errors. Always be sure to change these accounts through Config Manager as it will force you to back up your key.
TL;DR: The 503 response from the IIS machine, Service Unavailable, is the result of repeated application crashes. Since the w3wp.exe worker process, created by IIS to execute a web application, is crashing frequently, the respective IIS application pool is turned off. This is a feature of IIS, at Application Pool level, called Rapid-Fail Protection. It helps prevent consuming valuable system ...
