HTTP 226 IM Used vs 503 Service Unavailable
HTTP 226 (IM Used) is a 2xx Success response, while 503 (Service Unavailable) is a 5xx Server Error response. 226 indicates that the server has fulfilled a GET request for the resource, and the response is a representation of the result of one or more instance-manipulations. In contrast, 503 means that the server is temporarily unable to handle the request due to maintenance or overload. Should include a Retry-After header.
Description
The server has fulfilled a GET request for the resource, and the response is a representation of the result of one or more instance-manipulations.
When You See It
When using delta encoding to reduce bandwidth.
How to Fix
Rarely encountered. The response uses Instance Manipulations (IM) as specified.
Description
The server is temporarily unable to handle the request due to maintenance or overload. Should include a Retry-After header.
When You See It
During maintenance windows, server overload, or when the application pool is exhausted.
How to Fix
Wait and retry. Check the Retry-After header. Scale up servers if it's a capacity issue.
Key Differences
226 is a 2xx Success response, while 503 is a 5xx Server Error response.
HTTP 226: The server has fulfilled a GET request for the resource, and the response is a representation of the result of one or more instance-manipulations.
HTTP 503: The server is temporarily unable to handle the request due to maintenance or overload. Should include a Retry-After header.
You encounter 226 when when using delta encoding to reduce bandwidth.
You encounter 503 when during maintenance windows, server overload, or when the application pool is exhausted.
When to Use Which
For 226 (IM Used): Rarely encountered. The response uses Instance Manipulations (IM) as specified. For 503 (Service Unavailable): Wait and retry. Check the Retry-After header. Scale up servers if it's a capacity issue.