illegal_argument_exception when calling the Field Capabilities API

[gtoth93]

Elastic.Clients.Elasticsearch version: 8.15.6

Elasticsearch version: 7.17 / 8.15

.NET runtime version: 8.0

Operating system version: Windows 11

Description of the problem including expected versus actual behavior:
When calling the field capabilities API, the request fails because the fields are added to the request body instead of being added to request params.
This is how I call the API:

var fieldCapsResponse = await Connection
    .NewClient
    .FieldCapsAsync(Connection.Index, request => request.Fields(new ElasticsearchField("*")).IncludeUnmapped(), cancellationToken)
    .ConfigureAwait(false);

As a workaround I called the API with the low level client and added fields to the request parameters manually, this way the request succeeds:

var requestQueryParams = new FieldCapsRequestParameters
{
    IncludeUnmapped = true
};
requestQueryParams.SetQueryString("fields", "*");

var fieldCapsResponse = await Connection
    .NewClient
    .Transport
    .RequestAsync<FieldCapsResponse>(
        HttpMethod.GET,
        $"/{Connection.Index}/_field_caps",
        null,
        requestQueryParams,
        cancellationToken)
    .ConfigureAwait(false);

Expected behavior
When calling the Field Capabilities API, fields should be added to the query parameters instead of the request body.

Provide ConnectionSettings (if relevant):

Provide DebugInformation (if relevant):
Unsuccessful (400) low level call on POST: /reefreview-dev-project-66/_field_caps?pretty=true&error_trace=true&include_unmapped=true
Exception: Request failed to execute. Call: Status code 400 from: POST /reefreview-dev-project-66/_field_caps?pretty=true&error_trace=true&include_unmapped=true. ServerError: Type: illegal_argument_exception Reason: "specified fields can't be null or empty"

# Audit trail of this API call:
- [1] BadResponse: Node: http://elastic:redacted@elasticsearch.local:9200/ Took: 00:00:00.0702640
# OriginalException: Elastic.Transport.TransportException: Request failed to execute. Call: Status code 400 from: POST /reefreview-dev-project-66/_field_caps?pretty=true&error_trace=true&include_unmapped=true. ServerError: Type: illegal_argument_exception Reason: "specified fields can't be null or empty"
# Request:
{
"fields": [
"*"
]
}
# Response:
{
"error" : {
"root_cause" : [
{
"type" : "illegal_argument_exception",
"reason" : "specified fields can't be null or empty",
"stack_trace" : "[specified fields can't be null or empty]; nested: IllegalArgumentException[specified fields can't be null or empty];\n\tat org.elasticsearch.ElasticsearchException.guessRootCauses(ElasticsearchException.java:668)\n\tat org.elasticsearch.ElasticsearchException.generateFailureXContent(ElasticsearchException.java:596)\n\tat org.elasticsearch.rest.BytesRestResponse.build(BytesRestResponse.java:140)\n\tat org.elasticsearch.rest.BytesRestResponse.(BytesRestResponse.java:101)\n\tat org.elasticsearch.rest.BytesRestResponse.(BytesRestResponse.java:81)\n\tat org.elasticsearch.rest.RestController.dispatchRequest(RestController.java:342)\n\tat org.elasticsearch.rest.RestController.tryAllHandlers(RestController.java:405)\n\tat org.elasticsearch.rest.RestController.dispatchRequest(RestController.java:252)\n\tat org.elasticsearch.http.AbstractHttpServerTransport.dispatchRequest(AbstractHttpServerTransport.java:384)\n\tat org.elasticsearch.http.AbstractHttpServerTransport.handleIncomingRequest(AbstractHttpServerTransport.java:478)\n\tat org.elasticsearch.http.AbstractHttpServerTransport.incomingRequest(AbstractHttpServerTransport.java:358)\n\tat org.elasticsearch.http.netty4.Netty4HttpRequestHandler.channelRead0(Netty4HttpRequestHandler.java:35)\n\tat org.elasticsearch.http.netty4.Netty4HttpRequestHandler.channelRead0(Netty4HttpRequestHandler.java:19)\n\tat io.netty.channel.SimpleChannelInboundHandler.channelRead(SimpleChannelInboundHandler.java:99)\n\tat io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:444)\n\tat io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:420)\n\tat io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:412)\n\tat org.elasticsearch.http.netty4.Netty4HttpPipeliningHandler.channelRead(Netty4HttpPipeliningHandler.java:48)\n\tat io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:442)\n\tat io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:420)\n\tat io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:412)\n\tat io.netty.handler.codec.MessageToMessageDecoder.channelRead(MessageToMessageDecoder.java:103)\n\tat io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:444)\n\tat io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:420)\n\tat io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:412)\n\tat io.netty.handler.codec.MessageToMessageDecoder.channelRead(MessageToMessageDecoder.java:103)\n\tat io.netty.handler.codec.MessageToMessageCodec.channelRead(MessageToMessageCodec.java:111)\n\tat io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:442)\n\tat io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:420)\n\tat io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:412)\n\tat io.netty.handler.codec.MessageToMessageDecoder.channelRead(MessageToMessageDecoder.java:103)\n\tat io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:444)\n\tat io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:420)\n\tat io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:412)\n\tat io.netty.handler.codec.MessageToMessageDecoder.channelRead(MessageToMessageDecoder.java:103)\n\tat io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:444)\n\tat io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:420)\n\tat io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:412)\n\tat io.netty.handler.codec.ByteToMessageDecoder.fireChannelRead(ByteToMessageDecoder.java:346)\n\tat io.netty.handler.codec.ByteToMessageDecoder.channelRead(ByteToMessageDecoder.java:318)\n\tat io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:444)\n\tat io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:420)\n\tat io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:412)\n\tat io.netty.handler.timeout.IdleStateHandler.channelRead(IdleStateHandler.java:286)\n\tat io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:442)\n\tat io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:420)\n\tat io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:412)\n\tat io.netty.handler.codec.MessageToMessageDecoder.channelRead(MessageToMessageDecoder.java:103)\n\tat io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:444)\n\tat io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:420)\n\tat io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:412)\n\tat io.netty.channel.DefaultChannelPipeline$HeadContext.channelRead(DefaultChannelPipeline.java:1410)\n\tat io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:440)\n\tat io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:420)\n\tat io.netty.channel.DefaultChannelPipeline.fireChannelRead(DefaultChannelPipeline.java:919)\n\tat io.netty.channel.nio.AbstractNioByteChannel$NioByteUnsafe.read(AbstractNioByteChannel.java:166)\n\tat io.netty.channel.nio.NioEventLoop.processSelectedKey(NioEventLoop.java:788)\n\tat io.netty.channel.nio.NioEventLoop.processSelectedKeysPlain(NioEventLoop.java:689)\n\tat io.netty.channel.nio.NioEventLoop.processSelectedKeys(NioEventLoop.java:652)\n\tat io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:562)\n\tat io.netty.util.concurrent.SingleThreadEventExecutor$4.run(SingleThreadEventExecutor.java:997)\n\tat io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74)\n\tat java.base/java.lang.Thread.run(Thread.java:840)\nCaused by: java.lang.IllegalArgumentException: specified fields can't be null or empty\n\tat org.elasticsearch.action.fieldcaps.FieldCapabilitiesRequest.fields(FieldCapabilitiesRequest.java:128)\n\tat org.elasticsearch.rest.action.RestFieldCapabilitiesAction.prepareRequest(RestFieldCapabilitiesAction.java:51)\n\tat org.elasticsearch.rest.BaseRestHandler.handleRequest(BaseRestHandler.java:86)\n\tat org.elasticsearch.rest.RestController.dispatchRequest(RestController.java:340)\n\t... 57 more\n"
}
],
"type" : "illegal_argument_exception",
"reason" : "specified fields can't be null or empty",
"stack_trace" : "java.lang.IllegalArgumentException: specified fields can't be null or empty\n\tat org.elasticsearch.action.fieldcaps.FieldCapabilitiesRequest.fields(FieldCapabilitiesRequest.java:128)\n\tat org.elasticsearch.rest.action.RestFieldCapabilitiesAction.prepareRequest(RestFieldCapabilitiesAction.java:51)\n\tat org.elasticsearch.rest.BaseRestHandler.handleRequest(BaseRestHandler.java:86)\n\tat org.elasticsearch.rest.RestController.dispatchRequest(RestController.java:340)\n\tat org.elasticsearch.rest.RestController.tryAllHandlers(RestController.java:405)\n\tat org.elasticsearch.rest.RestController.dispatchRequest(RestController.java:252)\n\tat org.elasticsearch.http.AbstractHttpServerTransport.dispatchRequest(AbstractHttpServerTransport.java:384)\n\tat org.elasticsearch.http.AbstractHttpServerTransport.handleIncomingRequest(AbstractHttpServerTransport.java:478)\n\tat org.elasticsearch.http.AbstractHttpServerTransport.incomingRequest(AbstractHttpServerTransport.java:358)\n\tat org.elasticsearch.http.netty4.Netty4HttpRequestHandler.channelRead0(Netty4HttpRequestHandler.java:35)\n\tat org.elasticsearch.http.netty4.Netty4HttpRequestHandler.channelRead0(Netty4HttpRequestHandler.java:19)\n\tat io.netty.channel.SimpleChannelInboundHandler.channelRead(SimpleChannelInboundHandler.java:99)\n\tat io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:444)\n\tat io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:420)\n\tat io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:412)\n\tat org.elasticsearch.http.netty4.Netty4HttpPipeliningHandler.channelRead(Netty4HttpPipeliningHandler.java:48)\n\tat io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:442)\n\tat io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:420)\n\tat io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:412)\n\tat io.netty.handler.codec.MessageToMessageDecoder.channelRead(MessageToMessageDecoder.java:103)\n\tat io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:444)\n\tat io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:420)\n\tat io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:412)\n\tat io.netty.handler.codec.MessageToMessageDecoder.channelRead(MessageToMessageDecoder.java:103)\n\tat io.netty.handler.codec.MessageToMessageCodec.channelRead(MessageToMessageCodec.java:111)\n\tat io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:442)\n\tat io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:420)\n\tat io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:412)\n\tat io.netty.handler.codec.MessageToMessageDecoder.channelRead(MessageToMessageDecoder.java:103)\n\tat io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:444)\n\tat io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:420)\n\tat io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:412)\n\tat io.netty.handler.codec.MessageToMessageDecoder.channelRead(MessageToMessageDecoder.java:103)\n\tat io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:444)\n\tat io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:420)\n\tat io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:412)\n\tat io.netty.handler.codec.ByteToMessageDecoder.fireChannelRead(ByteToMessageDecoder.java:346)\n\tat io.netty.handler.codec.ByteToMessageDecoder.channelRead(ByteToMessageDecoder.java:318)\n\tat io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:444)\n\tat io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:420)\n\tat io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:412)\n\tat io.netty.handler.timeout.IdleStateHandler.channelRead(IdleStateHandler.java:286)\n\tat io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:442)\n\tat io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:420)\n\tat io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:412)\n\tat io.netty.handler.codec.MessageToMessageDecoder.channelRead(MessageToMessageDecoder.java:103)\n\tat io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:444)\n\tat io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:420)\n\tat io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:412)\n\tat io.netty.channel.DefaultChannelPipeline$HeadContext.channelRead(DefaultChannelPipeline.java:1410)\n\tat io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:440)\n\tat io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:420)\n\tat io.netty.channel.DefaultChannelPipeline.fireChannelRead(DefaultChannelPipeline.java:919)\n\tat io.netty.channel.nio.AbstractNioByteChannel$NioByteUnsafe.read(AbstractNioByteChannel.java:166)\n\tat io.netty.channel.nio.NioEventLoop.processSelectedKey(NioEventLoop.java:788)\n\tat io.netty.channel.nio.NioEventLoop.processSelectedKeysPlain(NioEventLoop.java:689)\n\tat io.netty.channel.nio.NioEventLoop.processSelectedKeys(NioEventLoop.java:652)\n\tat io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:562)\n\tat io.netty.util.concurrent.SingleThreadEventExecutor$4.run(SingleThreadEventExecutor.java:997)\n\tat io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74)\n\tat java.base/java.lang.Thread.run(Thread.java:840)\n"
},
"status" : 400
}

# TCP states:
Established: 1815
TimeWait: 161
CloseWait: 7

# ThreadPool statistics:
Worker:
Busy: 3
Free: 32764
Min: 8
Max: 32767
IOCP:
Busy: 0
Free: 1000
Min: 1
Max: 1000

[flobernd]

Hi @gtoth93 ,

you are mentioning 7.17 / 8.15 as the ES version.

Could you please confirm that the request fails for both versions? According to our specification, it should be allowed to pass the fields in the request body since version 8.5 which means that the request should only fail vs. the 7.17 instance.

[github-actions]

This issue is stale because it has been open 5 days with no activity. Remove stale label or comment or this will be closed in 2 days.

[github-actions]

This issue was closed because it has been stalled for 2 days with no activity.

[gtoth93]

@flobernd I have retested this, and you are correct, the high level request does work with 8.15, this issue can be closed.