Invalid Accept header results in 500 and a logged exception.

[barchetta]

Environment Details

• Helidon Version: 4.0.7, 3.2.7, 2.6.7
• Helidon SE

---

Problem Description

If you make a request with a malformed Accept header the server logs an exception and returns an Http status of 500. One would expect a more restrained response, for example: log (at most) a warning and return a 400.

I was able to reproduce some variant of this on Helidon 2, 3 and 4.

Steps to reproduce

Generate the a Quickstart SE project and start it. Then do (note badly formed mime type application.json):

curl -v -H 'Accept: application.json' -X GET http://localhost:8080/observe/metrics

The server returns 500:

> GET /observe/metrics HTTP/1.1
> Host: localhost:8080
> User-Agent: curl/8.4.0
> Accept: application.json
>
< HTTP/1.1 500 Internal Server Error
< Date: Tue, 16 Apr 2024 14:45:14 -0700
< Connection: keep-alive
< Content-Length: 41
< Content-Type: text/plain
<
* Connection #0 to host localhost left intact
Cannot parse media type: application.json

and logs an exception:

2024.04.16 14:45:14.704 Internal server error
io.helidon.http.RequestException: Cannot parse media type: application.json
	at io.helidon.http.RequestException$Builder.build(RequestException.java:139)
	at io.helidon.webserver.http.ErrorHandlers.unhandledError(ErrorHandlers.java:203)
	at io.helidon.webserver.http.ErrorHandlers.lambda$handleError$1(ErrorHandlers.java:182)
	at java.base/java.util.Optional.ifPresentOrElse(Optional.java:198)
	at io.helidon.webserver.http.ErrorHandlers.handleError(ErrorHandlers.java:181)
	at io.helidon.webserver.http.ErrorHandlers.runWithErrorHandling(ErrorHandlers.java:118)
	at io.helidon.webserver.http.Filters$FilterChainImpl.proceed(Filters.java:121)
	at io.helidon.webserver.observe.metrics.MetricsFeature.lambda$configureVendorMetrics$2(MetricsFeature.java:90)
	at io.helidon.webserver.http.Filters$FilterChainImpl.proceed(Filters.java:119)
	at io.helidon.webserver.http.Filters.executeFilters(Filters.java:87)
	at io.helidon.webserver.http.Filters.lambda$filter$0(Filters.java:83)
	at io.helidon.webserver.http.ErrorHandlers.runWithErrorHandling(ErrorHandlers.java:75)
	at io.helidon.webserver.http.Filters.filter(Filters.java:83)
	at io.helidon.webserver.http.HttpRoutingImpl.route(HttpRoutingImpl.java:73)
	at io.helidon.webserver.http1.Http1Connection.route(Http1Connection.java:357)
	at io.helidon.webserver.http1.Http1Connection.handle(Http1Connection.java:194)
	at io.helidon.webserver.ConnectionHandler.run(ConnectionHandler.java:165)
	at io.helidon.common.task.InterruptableTask.call(InterruptableTask.java:47)
	at io.helidon.webserver.ThreadPerTaskExecutor$ThreadBoundFuture.run(ThreadPerTaskExecutor.java:239)
	at java.base/java.lang.VirtualThread.run(VirtualThread.java:309)
Caused by: java.lang.IllegalArgumentException: Cannot parse media type: application.json
	at io.helidon.common.media.type.MediaTypeImpl.parse(MediaTypeImpl.java:38)
	at io.helidon.common.media.type.MediaTypes.create(MediaTypes.java:177)
	at io.helidon.http.HttpMediaType$Builder.parse(HttpMediaType.java:313)
	at io.helidon.http.HttpMediaType.create(HttpMediaType.java:76)
	at io.helidon.http.ServerRequestHeadersImpl.acceptedTypes(ServerRequestHeadersImpl.java:88)
	at io.helidon.http.ServerRequestHeaders.bestAccepted(ServerRequestHeaders.java:139)
	at io.helidon.webserver.observe.metrics.MetricsFeature.bestAccepted(MetricsFeature.java:131)
	at io.helidon.webserver.observe.metrics.MetricsFeature.getMatching(MetricsFeature.java:184)
	at io.helidon.webserver.observe.metrics.MetricsFeature.getAll(MetricsFeature.java:177)
	at io.helidon.webserver.http.HttpRoutingImpl$RoutingExecutor.doRoute(HttpRoutingImpl.java:165)
	at io.helidon.webserver.http.HttpRoutingImpl$RoutingExecutor.call(HttpRoutingImpl.java:124)
	at io.helidon.webserver.http.HttpRoutingImpl$RoutingExecutor.call(HttpRoutingImpl.java:102)
	at io.helidon.webserver.http.ErrorHandlers.runWithErrorHandling(ErrorHandlers.java:75)
	... 14 more

[spericas]

I can take a look, will start with 4.x