503 service unavailable Error Solution Explanation

1. Open the web page and visit 503 service unavailable, but it can be accessed normally after refreshing 1

1. If this happens, most of them are caused by the website exceeding the system resources and exceeding the IIS limit. We need to increase the number of IIS connections to solve it.

2. Does the website not limit the number of IIS connections, or does it prompt 503 service unavailable

This situation is mostly the use of access database sites, through a simple analysis can be concluded that the ACCESS engine when. A further step of troubleshooting reveals that a few files caused "catastrophic failure" of the ACCESS engine and "no object reference set to an instance of an object" errors. After being repaired by the document doctor, the system will return to normal.

3. When browsing an Windows SharePoint Services Web site, prompt: Service Unavailable

This problem occurs because the application pool for the virtual server is not properly configured in Microsoft Internet Information Service (IIS) 6.0.

Solution:

1. First, we need to verify that the virtual server has the application pool configured correctly. The default application pool is MSSharePointPortalAppPool.

Click Start to select Administrative Tools, and then click Internet Information Services (IIS) Manager. Open ServerName, expand Web Sites, right-click the virtual server, and then click Properties. Click the Home Directory tab, and the application pools configured for the virtual server are listed in the Application Pool box. Just click OK.

2. Verify that the application pool account is a member of the IIS_WPG and STS_WPG groups on the server.

3. Restart IIS to recycle the application pool.

4. 503 service unavailable due to incorrect loading of ISAPI filter

If the ISAPI filter is not loaded successfully, it will cause Service unavailable for any Web site 1 visit. This time, it needs to be resolved according to the reason of the load failure, or the ISAPI filter should be deleted.