APMIA agent missing in APM UI

Products

• APM

Issue/Introduction

We restarted apmia agent and the agent disappeared in APM. We are using the apmia agent for collecting ASM metrics. We also see few other agents disconnected. There are many other agents connected and reporting data in the APM UI. Our agents connect to DX APM SAAS tenant.

We tried with new agent token and also tried with tenant token, neither has worked.

We see following error in APMIAWrapper.log and IntroscopeAgent.log.

[ERROR] [IntroscopeAgent.IsengardMessaging] WebSocket handshake failed:Invalid handshake response getStatus: 403 Forbidden
[WARN] [IntroscopeAgent.ConnectionThread] Failed to connect to the Introscope Enterprise Manager at <hostname>:443,com.wily.isengard.client.transport.websocket.SSLWebSocketFactory (io.netty.handler.codec.http.websocketx.WebSocketHandshakeException:Invalid handshake response getStatus: 403 Forbidden).

[ERROR] [IntroscopeAgent.IsengardMessaging] WebSocket handshake failed:Invalid handshake response getStatus: 400 Bad Request
[WARN] [IntroscopeAgent.ConnectionThread] Failed to connect to the Introscope Enterprise Manager at apmgw.dxi-na1.saas.broadcom.com:443,com.wily.isengard.client.transport.websocket.SSLWebSocketFactory (io.netty.handler.codec.http.websocketx.WebSocketClientHandshakeException:Invalid handshake response getStatus: 400 Bad Request).

Environment

Release : 20.2

Component : APM Agents

Resolution

SAAS team restarted the EM services for the tenant.
We see that all agents are connecting good and reporting metrics in APM UI. 
We restarted ASM agent a couple of times and ASM agent is continue to connect and report metrics in APM UI.
If agents are connecting to DX APM SAAS, test the issue using new agent token. If this does not help, contact  APM Support.