If you want to ignore an error with a specific code and type while testing, you can configure the Ignore Error Codes option in the test target settings. If the system detects a response with the specified error type and code, the response will be considered as successful and its status will be changed to OK. Note that ignored errors will not be reflected on the reports and can’t be tracked down.
You can find a comprehensive list of Error Codes in the HTTP Status Codes List | HTTP Error Codes Explained article of this wiki.