DevOps Relase Failing with Downloading task: IISWebAppManagementOnMachine

Looks like you're hitting a known DevOps task download stall.
While your deployment group appears online, the pipeline hangs specifically when downloading the IISWebAppDeploymentOnMachineGroup task, eventually timing out after 1200 seconds.

Here’s what might be causing it — and how you can try resolving it:

Possible Causes & Fixes
Agent Version Mismatch / Corruption

Ensure your agent is up to date. Old agents can struggle with certain task versions.

Action: Manually update or reconfigure the agent on the affected machine(s).

Network Restrictions (Firewall, Proxy, etc.)

DevOps agents pull tasks over HTTPS. Even minor DNS delays or firewall rules can block task retrieval.

Action: Try to manually access this endpoint from your agent machine:
https://vstsagentpackage.azureedge.net/
If blocked, you’ll need to whitelist Azure DevOps endpoints.

Corrupted Task Cache

DevOps agents cache tasks locally. If the cache is corrupt or partial, it can cause endless retries.

Action:
a. Stop the agent service
b. Delete %ProgramData%\Microsoft\Azure DevOps\Agent\_work\_tasks
c. Restart the agent

Task Version Issue (0.234.0)

This version of IISWebAppDeploymentOnMachineGroup might have been updated or temporarily pulled.

Action:
a. Try hard-coding an earlier working version in your YAML or pipeline definition
b. Check task availability in DevOps marketplace or CLI

Agent Capacity / System Limits

If you're using self-hosted agents, ensure system resources (disk, RAM, network throughput) are sufficient. A bottleneck there can silently break downloads.

Fallback Suggestion
If the above doesn’t resolve it:

Set up a new deployment agent on a clean VM and rebind it to your deployment group.

Confirm if issue reproduces.

If new agent works, original one likely had local environment corruption.

Let me know what you find — this error is common in on-prem agent setups, but solvable with targeted cleanup. Good luck!

Below the workarounds:

1. Manually Clear Task Cache on Agent Machine
- Navigate to C:\azagent\A20\_work\_tasks
- Delete the folders for IISWebAppDeploymentOnMachineGroup and IISWebAppManagementOnMachineGroup
- Restart the agent service
2. Check Agent Logs for Network Errors
Look for any signs of failed HTTP requests or DNS issues in the agent logs. You may need to whitelist task URLs or check proxy settings.
3. Update or Reinstall the Agent
If the agent is outdated or misconfigured, reinstalling it can resolve download and execution issues.
4. Switch to Inline PowerShell as a Temporary Workaround
If you're blocked and need to deploy urgently, consider replacing the IIS task with a custom PowerShell script that uses appcmd.exe or WebDeploy.