Default404Servlet means the request reached Mirth's embedded web server but no listener matched that path — almost always a base context path mismatch or a stopped channel. 405 Method Not Allowed means the path matched but the HTTP method (GET/POST/PUT) isn't what the listener accepts. Align the base context path and method with what the client sends.
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Get Help With a Broken Interface →What these responses actually mean
- Default404Servlet in the response means the request reached the embedded web server but no listener matched that path. The request fell through to the default handler.
- 405 Method Not Allowedmeans a path matched, but the HTTP method (GET/POST/PUT) you used isn't what the listener accepts.
Common causes and fixes
1. Base context path mismatch.The HTTP Listener's base context path must match exactly what the caller requests, including leading slash and case. If the listener is set to /fhir and the client calls /FHIR or /fhir/inconsistently, the path won't match and you get Default404Servlet. Align the configured base context path with the client URL.
2. Wrong HTTP method.If your listener is configured to accept POST and a client sends GET (or vice versa), you get a 405. Confirm the method the client uses matches the listener's allowed method. For FHIR endpoints, different operations use different methods — make sure each is handled.
3. Multiple listeners colliding on a port/path. Two HTTP listeners bound to overlapping paths on the same port can shadow each other. Give each a distinct base context path.
4. Trailing-slash and sub-path handling. A listener at /fhir may not automatically serve /fhir/Patient unless configured to handle sub-paths. Confirm whether your design needs path-pattern matching.
5. Channel not started.If the channel hosting the listener is stopped, the path won't be registered and requests fall through to the default servlet.
Step-by-step fix
- Confirm the channel with the HTTP listener is started.
- Compare the listener's base context path to the exact URL the client calls — match slash, case, and sub-path.
- Confirm the listener's allowed HTTP methodmatches the client's request method (405 = method mismatch).
- Check no other listener is bound to the same port/path.
- Re-test with the corrected URL and method; a matched request returns your channel's response instead of Default404Servlet.
How to prevent it
Standardize endpoint paths and document the method each accepts; keep one listener per path per port; and add a monitoring check that calls each endpoint with the expected method so a 405/404 regression is caught immediately — standard practice under managed support. Building FHIR endpoints on Mirth? See our Mirth FHIR server and FHIR integration services.
Endpoint still returning 404/405?
Send us the listener config and the request — we'll get your REST/FHIR endpoint responding correctly.
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