# MQTT Transmission Connection Lost Error **URL:** \ **Category:** Maker\ **Created:** [March 14, 2024, 4:46pm UTC](https://forum.inductiveautomation.com/t/mqtt-transmission-connection-lost-error/87354 "2024-03-14T16:46:31Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![Satyam\_Singh](https://avatars.discourse-cdn.com/v4/letter/s/977dab/32.png) [@Satyam\_Singh](https://forum.inductiveautomation.com/u/Satyam_Singh)\ **Post date:** [March 14, 2024, 4:46pm UTC](https://forum.inductiveautomation.com/t/mqtt-transmission-connection-lost-error/87354/1 "2024-03-14T16:46:31Z")
I am trying to setup Ignition MQTT Transmission to the AWS IoT Endpoint server with certificates and keys. I have followed the instruction as per the below link: [**[https://docs.chariot.io/display/CLD80/IBSNOW%3A+AWS+Quickstart](https://docs.chariot.io/display/CLD80/IBSNOW%3A+AWS+Quickstart)**] I have checked that AWS IoT certificates and keys are working fine but still MQTT Transmission is not able to connect AWS IoT Endpoint server. Please assist and let me know if you need any further information. Getting below error in the Ignition log: TahuClient 14Mar2024 22:06:57 ME-a2026340-4cb3-433c: connect with retry failed due to Connection lost org.eclipse.paho.client.mqttv3.MqttException: Connection lost at org.eclipse.paho.client.mqttv3.internal.CommsReceiver.run(CommsReceiver.java:197) at java.base/java.lang.Thread.run(Unknown Source) Caused by: java.io.EOFException: null at java.base/java.io.DataInputStream.readUnsignedByte(Unknown Source) at java.base/java.io.DataInputStream.readByte(Unknown Source) at org.eclipse.paho.client.mqttv3.internal.wire.MqttInputStream.readMqttWireMessage(MqttInputStream.java:92) at org.eclipse.paho.client.mqttv3.internal.CommsReceiver.run(CommsReceiver.java:137) ... 1 common frames omitted ---
**Author:** ![pturmel](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/pturmel/32/3295_2.png) [@pturmel](https://forum.inductiveautomation.com/u/pturmel)\ **Post date:** [March 14, 2024, 5:05pm UTC](https://forum.inductiveautomation.com/t/mqtt-transmission-connection-lost-error/87354/2 "2024-03-14T17:05:39Z")
> [@Satyam\_Singh](#): > > Caused by: java.io.EOFException: null That almost certainly means some firewall along the network path is killing the connection. Possibly using a deep packet inspection that doesn't like MQTT. ---
**Author:** ![TChenier](https://avatars.discourse-cdn.com/v4/letter/t/d6d6ee/32.png) [@TChenier](https://forum.inductiveautomation.com/u/TChenier)\ **Post date:** [March 14, 2024, 5:36pm UTC](https://forum.inductiveautomation.com/t/mqtt-transmission-connection-lost-error/87354/3 "2024-03-14T17:36:59Z")
Also, be aware the AWS IoT broker has a limit on message size. If Transmission publishes a birth with a large tag map that exceeds this limit, IoT Core will drop the connection. > [@MQTT Transmission tag limit](https://forum.inductiveautomation.com/t/mqtt-transmission-tag-limit/82277/2): > > This is more likely due to AWS IoT Core's message size limitation of 128 KB. When a client publishes a message that exceeds the limit, IoT Core will drop the connection. [https://aws.amazon.com/iot-core/pricing/#:~:text=You%20can%20send%20and%20receive,metered%20in%205%20KB%20increments.](https://aws.amazon.com/iot-core/pricing/#:~:text=You%20can%20send%20and%20receive,metered%20in%205%20KB%20increments.) ---
**Author:** ![marioishikawa](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/marioishikawa/32/7352_2.png) [@marioishikawa](https://forum.inductiveautomation.com/u/marioishikawa)\ **Post date:** [March 20, 2024, 5:50pm UTC](https://forum.inductiveautomation.com/t/mqtt-transmission-connection-lost-error/87354/4 "2024-03-20T17:50:22Z")
This error message also appears for a very simple issue: wrong password. It was my case when testing with highbyte broker.