How to fix IIS 503 error, Service unavailable?

I am new to learning iis. According to the iis official documentation, I tried to create a site. But got this error. I found that the default app pool automatically stops. The iis official documentation is really not suitable for new learning. If anyone can help me, please make the solution easier to understand. Thanks in advance.

Vague descriptions alone do not allow community members to understand the problem you are experiencing. Please describe what error you got and you'd better provide detailed error message.

What kind of site? I don't think raw HTML and JavaScript will give you 503 errors that easily, so you need to tell more about the site.

Thank you all. Currently I don't think it's relevant to the project I created. My site is under default application pool. I deleted all except default site. Running the default site still gets 503 errors and no more error messages. I've noticed that the default app pool always stop automatically, why? Thanks for the help.

1 Answer 1

HTTP Error 503. 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.

To determine the exact reason why the application pool was disabled or stopped, open Event Viewer, navigate to the System log, and look for Error or Warning events whose source is Windows Process Activation Service ( WAS ). WAS is responsible for starting/stopping application pools and tracking worker processes in IIS.

Application pools can fail for a variety of reasons, such as unhandled exceptions in your code, expired passwords for application pool identities, or other reasons. By default, IIS is configured to disable a failing application pool if its worker process crashes five times in a row within five minutes. This setting is called Rapid-Fail Protection and is available under the application pool's advanced settings.You can modify the corresponding parameters as needed.

One possible reason for this to happen is that the application pool in IIS is configured to run under a custom account which does not exist or an incorrect password was provided or the password has been changed. Please check which account it is using in the advanced properties of the IIS application pool.

You need to enable the application pool corresponding to your website. If you receive errors or warnings related to the application pool identity, make sure that the identity's username and password are correct. If using a custom username, make sure its password has not expired. If possible, set the user's password to never expire.