Use the HTTP status first, then check the probe-specific error code and message to identify the category. A 4xx response usually indicates a client or authorization issue, while a 5xx response usually indicates a server-side problem. The message often adds the most direct clue about whether the failure comes from the request, access state, or system behavior.
API Probe Error Codes
Reference the meanings, categories, and likely causes of probe errors at a glance in this technical lookup guide.
View error reference4xx/5xxHTTP status classes covered for request, auth, and server-side failures.
Probe codesProbe-specific error codes mapped to their message meanings.
3 categoriesClient, authorization, and server issues separated for fast lookup.
1 referenceA concise index for API testers, QA teams, and developers.
Main error groups
Client errors
These typically align with 4xx responses and point to invalid requests, missing fields, or unsupported values. The probe code and message usually indicate a request-side issue rather than a system fault.
Authentication errors
These are commonly tied to authorization failures such as invalid credentials, expired access, or insufficient permission. The response message usually confirms that the probe could not authenticate the request.
Server errors
These generally map to 5xx responses and indicate a service-side failure, timeout, or unavailable dependency. They are usually treated as system issues rather than client mistakes.
Probe-specific codes
In addition to HTTP status, the probe may return its own error code for more precise lookup. These codes help distinguish overlapping cases where similar HTTP statuses have different meanings.
How to read an error response
What does the probe error message mean?
The message summarizes the failure in human-readable form. It often names the invalid field, missing permission, unavailable resource, or internal condition associated with the error.
How do I tell client errors from server errors?
Client errors are usually in the 4xx range and indicate something in the request or credentials is not acceptable. Server errors are usually in the 5xx range and indicate the system could not complete the operation.
Are all 4xx errors authentication problems?
No. Some 4xx responses are auth-related, but others point to request validation, unsupported input, or a missing resource. The probe code and message help distinguish the exact cause.
What if the HTTP status and probe code seem different?
Use both together. The HTTP status gives the broad class, while the probe-specific code narrows the exact condition and is often the best lookup key for documentation.
When is an error likely caused by the system?
If the response is in the 5xx range or the message indicates an internal failure, timeout, or unavailable dependency, it is usually treated as a server-side issue.