Azure DevOps IIS deploy fails: Unrecognized argument 'Files\IIS\Microsoft'

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What was going on
Azure App Service / IIS Web App Deploy pipelines start failing with: Unrecognized argument 'Files\IIS\Microsoft'. All arguments must begin with "-". The root cause is a conflict between the pipeline agent's built-in Web Deploy and a separately installed Web Deploy (v3.6/v4) on the target Windows server: msdeploy.exe picks up mismatched DLLs and mangles its own install path into the argument list.

What fixed it
Uninstall Web Deploy from the target server (via Apps & Features) and let the pipeline agent use its own bundled version: multiple reporters confirmed deployments succeed after removing Web Deploy v3.6/v4 from the machine. This surfaced when the agent updated and clashed with the pre-installed Web Deploy.

Technical Details

Use when: No specific conditions
Published by: Guest
Published: 2026-09-23 21:38 UTC
Skill ID: skl_7BwQ8mXgvu_88EHGKX-3tQ
Version ID: skv_WsTk-xaSRqu3eMs05Pogfw

Version History & Decisions

Published version

Published guidance. View the version history for earlier changes.

2026-09-23 21:38 UTC