I m starting to use Ktor to connect to a new endpoint and am

Question

I m starting to use Ktor to connect to a new endpoint and am getting the following I don t have any control over headers returned anyone know if there s way to work around this ```io ktor http IllegalHeaderValueException Header value utmvazauvysSB=TIAZsaY path= Max Age=900 contains illegal character code 1 at io ktor http HttpHeaders checkHeaderValue HttpHeaders kt 153 at io ktor http HeadersBuilder validateValue Headers kt 43 at io ktor util StringValuesBuilder appendAll StringValues kt 208 at io ktor client engine android AndroidClientEngine execute AndroidClientEngine kt 92 ``` I can open url in browser for example and do see valid json returned

hhariri · Answer

Do you have a case to repro

John O&apos;Reilly · Answer

here s an example endpoint that I m just doing normal get against I can try and put sample code together as well if needed ```<https data smartdublin ie cgi bin rtpi routeinformation operator=be amp routeid=401>```

hhariri · Answer

Apologies for delay I just tried this with 1 3 72 and it seems to work fine What Accept header are you passing in

John O&apos;Reilly · Answer

Thanks for checking won t be able to confirm until later but is there particular one we should be passing in don t think I had anything other than default default for that endpoint should be json

John O&apos;Reilly · Answer

hmm just tried it now and it worked Perhaps owners of that endpoint made some changes to what was in response headers so it no longer has that illegal character

John O&apos;Reilly · Answer

It s back happening again is there any way for example to stop ktor performing that check ```main coroutine 1 INFO io ktor client HttpClient REQUEST main coroutine 1 INFO io ktor client HttpClient METHOD HttpMethod value=GET main coroutine 1 INFO io ktor client HttpClient COMMON HEADERS main coroutine 1 INFO io ktor client HttpClient gt Accept application json main coroutine 1 INFO io ktor client HttpClient gt Accept Charset UTF 8 main coroutine 1 INFO io ktor client HttpClient CONTENT HEADERS main coroutine 1 INFO io ktor client HttpClient BODY Content Type null main coroutine 2 INFO io ktor client HttpClient BODY START main coroutine 2 INFO io ktor client HttpClient main coroutine 2 INFO io ktor client HttpClient BODY END main coroutine 1 INFO io ktor client HttpClient REQUEST failed with exception io ktor http IllegalHeaderValueException Header value utmvazauvysSB=mNVidUA path= Max Age=900 contains illegal character code 1 io ktor http IllegalHeaderValueException Header value utmvazauvysSB=mNVidUA path= Max Age=900 contains illegal character code 1 at io ktor http HttpHeaders checkHeaderValue HttpHeaders kt 153 at io ktor http HeadersBuilder validateValue Headers kt 43 at io ktor util StringValuesBuilder appendAll StringValues kt 208 at io ktor client engine android AndroidClientEngine execute AndroidClientEngine kt 92 at io ktor client engine HttpClientEngine$executeWithinCallContext$2 invokeSuspend HttpClientEngine kt 83 at kotlin coroutines jvm internal BaseContinuationImpl resumeWith ContinuationImpl kt 33 at kotlinx coroutines DispatchedTask run DispatchedTask kt 56 at kotlinx coroutines scheduling CoroutineScheduler runSafely CoroutineScheduler kt 571 at kotlinx coroutines scheduling CoroutineScheduler$Worker executeTask CoroutineScheduler kt 738 at kotlinx coroutines scheduling CoroutineScheduler$Worker runWorker CoroutineScheduler kt 678 at kotlinx coroutines scheduling CoroutineScheduler$Worker run CoroutineScheduler kt 665 ```

John O&apos;Reilly · Answer

< hhariri> do you know of any workarounds for this Unfortunately as mentioned this is endpoint I have no control over so can t affect what s in the response headers I m using ktor successfully in a few other projects but obviously this is blocker for this particular one

hhariri · Answer

Can you reproduce for us in any way

John O&apos;Reilly · Answer

I ll try to put small sample together hopefully it will still be failing at time you run it though slightly smiling face I guess there s some level of randomness to what gets included in those header values that triggers this

John O&apos;Reilly · Answer

Following should hopefully be pretty self contained code you should be able to run there ``` import io ktor client HttpClient import io ktor client engine cio CIO import io ktor client features json JsonFeature import io ktor client features json serializer KotlinxSerializer import io ktor client request get import io ktor client request parameter import io ktor client request url import kotlinx coroutines runBlocking import kotlinx serialization Serializable import kotlinx serialization json Json import kotlinx serialization json JsonConfiguration Serializable data class Stop val stopid String val shortname String val fullname String val latitude String val longitude String Serializable data class BusStopInformationResult val results List lt Stop gt class RTPIApi private val baseUrl = <https data smartdublin ie cgi bin rtpi> private val nonStrictJson = Json JsonConfiguration isLenient = true ignoreUnknownKeys = true private val client by lazy HttpClient CIO install JsonFeature serializer = KotlinxSerializer nonStrictJson suspend fun getBusStopInformation BusStopInformationResult return client get url $baseUrl busstopinformation parameter operator be fun main val rtpiApi = RTPIApi runBlocking rtpiApi getBusStopInformation ```

John O&apos;Reilly · Answer

using these dependencies ``` implementation io ktor ktor client core jvm 1 3 2 implementation io ktor ktor client json jvm 1 3 2 implementation io ktor ktor client serialization jvm 1 3 2 implementation io ktor ktor client cio 1 3 2 implementation org jetbrains kotlinx kotlinx serialization runtime 0 20 0 ```

John O&apos;Reilly · Answer

Running that in IntelliJ here and getting ```Exception in thread main io ktor http cio ParserException Character with code 1 is not allowed in header names HTTP 1 1 200 OKServer nginx 1 17 8Date Fri 17 Jul 2020 17 02 42 GMTContent Type application json charset=utf 8Content Length 1596054Connection keep aliveX Powered By ASP NETSet Cookie visid incap 1822411=6 TavgoATn2fIJqXLil94rLZEV8AAAAAQUIPAAAAAAA2pXqBkrH+X0bxcOBu7tLA expires=Sat 17 Jul 2021 08 40 34 GMT HttpOnly path= Domain= nationaltransport ieSet Cookie incap ses 535 1822411=2uPhR+2fyjexa0dYuLNsB7LZEV8AAAAAYXloqvhgqt+OzLpFszbb8Q== path= Domain= nationaltransport ieSet Cookie utmvmzauvysSB=vRnGmVILTRo path= Max Age=900Set Cookie utmvazauvysSB=nqVRlec path= Max Age=900 at io ktor http cio HttpParserKt characterIsNotAllowed HttpParser kt 279 at io ktor http cio HttpParserKt parseHeaderValue HttpParser kt 261 at io ktor http cio HttpParserKt parseHeaders HttpParser kt 119 at io ktor http cio HttpParserKt parseResponse HttpParser kt 73 at io ktor http cio HttpParserKt$parseResponse$1 invokeSuspend HttpParser kt at kotlin coroutines jvm internal BaseContinuationImpl resumeWith ContinuationImpl kt 33 at kotlinx coroutines DispatchedTask run DispatchedTask kt 56 at kotlinx coroutines scheduling CoroutineScheduler runSafely CoroutineScheduler kt 571 at kotlinx coroutines scheduling CoroutineScheduler$Worker executeTask CoroutineScheduler kt 738 at kotlinx coroutines scheduling CoroutineScheduler$Worker runWorker CoroutineScheduler kt 678 at kotlinx coroutines scheduling CoroutineScheduler$Worker run CoroutineScheduler kt 665 ```

hhariri · Answer

Reproduced and logged <https youtrack jetbrains com issue KTOR 860>

hhariri · Answer

There s definitely a strange character in there

hhariri · Answer

John O&apos;Reilly · Answer

It s likely there probably is something being done incorrectly by that endpoint but unfortunately it s one I don t have any control over

hhariri · Answer

It s <http ASP NET|ASP NET> For sure there s some nonstandard behaviour Typical of MS tech