Metric Behavior Changes After Upgrading DX APM Agent - Error Rate Increases abnormally

Products

• CA Application Performance Management (APM / Wily / Introscope)
• DX Application Performance Management

Issue/Introduction

Symptoms

You observe a significant change in metric behavior after upgrading your DX APM (Introscope) agent from version 10.7 or 20.x to version 25.x. While the absolute number of errors per interval remains consistent, the number of "Responses Per Interval" decreases significantly. This causes the calculated error rate (Errors/Responses) to increase abnormally, often triggering false-positive alerts on baseline deviations.

Environment

• Product: DX Application Performance Management (APM)
• Agent Versions: Upgrading from 10.7 or 20.x to 25.x
• Component: Java Agent / Introscope Agent

Cause

This issue typically occurs due to one of the following reasons:

1. Configuration Gaps: Custom settings from your previous IntroscopeAgent.profile (such as introscope.agent.errorsnapshots.ignore settings
   URL groups, clamps, smart instrumentation, or specific extensions) are not manually migrated to the new version 25.x profile.
2. Obsolete Tracers: Custom PBD files may use obsolete tracers that are removed in version 2x agents. For example, the AppMapMarker trace is obsolete and no longer supported in newer agent versions.

Resolution

To restore consistent metric behavior, you must perform the following steps:

1. Compare Agent Profiles: You must compare your previous IntroscopeAgent.profile with the new version 25.x profile. Ensure that all custom configurations for the following areas are migrated:

   • introscope.agent.urlgroup.group.alpha.*
   • ErrorDetector settings and filters, introscope.agent.errorsnapshots.ignore.*
   • Agent clamps and sampling rates
   • Smart Instrumentation levels
   • Extension bundle loading lists (introscope.agent.extensions.bundles.load)

2. Update Custom PBDs: You must review your custom PBD files for obsolete tracers. If you use AppMapMarker, you must remove or comment out these lines, as this tracer is removed in agent version 25.x and higher.

3. Validate Backend Metrics: You check the IntroscopeAgent.log to confirm the agent version and ensure that all expected extensions are loading without errors.