Chat Agent – Tool Execution Failure ("Downstream tool request failed")

RE: Chat Agent – Tool Execution Failure ("Downstream tool request failed")

Kaviarasu Mohan — Thu, 09 Jul 2026 12:22:58 GMT

Thank you for your reply.

I am new to Appian and Chat Agents. Could you please help me understand where I can check and find the idle timeout and read timeout settings for the downstream service?

Thank you for your assistance.

RE: Chat Agent – Tool Execution Failure ("Downstream tool request failed")

kapilsharma — Thu, 09 Jul 2026 11:52:18 GMT

Hi Kaviarasu Mohan ,

Server-Sent Events (SSE) require a long-lived, persistent HTTP connection to stream the LLM's response back to the user. If your downstream tool takes 30 to 60 seconds to execute, the AI pauses streaming.
I would suggest check the idle timeout and read timeout settings of your downstream service.

Moreover, the Appian chat component is waiting for the AI, and the AI is waiting for your tool to finish its work. If the tool hangs or takes too long, the underlying TCP socket simply gives up and drops.

Can you try increasing these timeouts to accommodate the maximum duration your longest tool takes to run, plus the standard LLM processing time.

RE: Chat Agent – Tool Execution Failure ("Downstream tool request failed")

Kaviarasu Mohan — Thu, 09 Jul 2026 11:41:46 GMT

Hi Kapil,

When i checked the log, this is the error message we are getting.

OkHttp ai-platform.ai-platform.svc.cluster.local/...] ERROR com.appiancorp.lcpapi.streaming.StepStreamingEventSourceListener - Upstream SSE stream failed for run
java.net.SocketException: Socket closed
at java.base/sun.nio.ch.NioSocketImpl.ensureOpenAndConnected(NioSocketImpl.java:165)
at java.base/sun.nio.ch.NioSocketImpl.beginRead(NioSocketImpl.java:236)
at java.base/sun.nio.ch.NioSocketImpl.implRead(NioSocketImpl.java:304)
at java.base/sun.nio.ch.NioSocketImpl.read(NioSocketImpl.java:355)
at java.base/sun.nio.ch.NioSocketImpl$1.read(NioSocketImpl.java:808)
at java.base/java.net.Socket$SocketInputStream.read(Socket.java:966)
at okio.InputStreamSource.read(JvmOkio.kt:93)
at okio.AsyncTimeout$source$1.read(AsyncTimeout.kt:128)
at okio.RealBufferedSource.request(RealBufferedSource.kt:209)
at okio.RealBufferedSource.require(RealBufferedSource.kt:202)
at okio.RealBufferedSource.readHexadecimalUnsignedLong(RealBufferedSource.kt:384)
at okhttp3.internal.http1.Http1ExchangeCodec$ChunkedSource.readChunkSize(Http1ExchangeCodec.kt:437)
at okhttp3.internal.http1.Http1ExchangeCodec$ChunkedSource.read(Http1ExchangeCodec.kt:416)
at okhttp3.internal.connection.Exchange$ResponseBodySource.read(Exchange.kt:281)
at okio.RealBufferedSource.select(RealBufferedSource.kt:232)
at okhttp3.internal.sse.ServerSentEventReader.processNextEvent(ServerSentEventReader.kt:50)
at okhttp3.internal.sse.RealEventSource.processResponse(RealEventSource.kt:75)
at okhttp3.internal.sse.RealEventSource.onResponse(RealEventSource.kt:46)
at okhttp3.internal.connection.RealCall$AsyncCall.run(RealCall.kt:519)
at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1136)
at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635)
at java.base/java.lang.Thread.run(Thread.java:840)

RE: Chat Agent – Tool Execution Failure ("Downstream tool request failed")

kapilsharma — Thu, 09 Jul 2026 11:12:52 GMT

Review Appian's integration logs (tomcat-stdOut.log or the specific integration error logs in the Monitoring view) for HTTP 429 Too Many Requests errors that correlate with the exact timestamps.