[ISS Support Case] Historian instability

Last updated: September 4th, 2026

Description

Historian stability: runs and collects, but intermittently degradesAA Event Storage not ready, data collection modules stop, connections time out, sometimes trend tool cant connect; rebooting Historian resolves temporarily. Logger shows AAHClient-related errors/timeouts. Historian is on a separate VLAN behind a firewall (ports opened per AVEVA KB). One prior incident where Metadata Server wouldnt stop; no third-party AV tools; Defender disabled

Author: Kevin Modlin
Published: September 4th, 2026

Details:

Product: Historian

Version: 2023 R2

Solution: [Solution is visible below when you're logged in and have a current subscription]

Date Created:	05/20/2026
Case:	103583

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