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Azure Migrate Assessment – Internal Error Occurred & Performance Coverage Showing “Not Applicable”

Bagavan Muniandy 5 Reputation points
2026-03-04T03:04:48.0833333+00:00

Issue Summary 1 : We are facing an issue with Azure Migrate where an internal system error occurs during assessment and the port are open able to communicate on one assessment .

Issue Summary 1 : another assessment Performance Coverage is showing as “Not applicable”, even though discovery is completed and the VM is successfully connected and there is no error

Azure Migrate
Azure Migrate

A central hub of Azure cloud migration services and tools to discover, assess, and migrate workloads to the cloud.


4 answers

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  1. Bharath Y P 7,240 Reputation points Microsoft External Staff Moderator
    2026-03-11T12:53:18.3+00:00

    Hello Bagavan Muniandy – it looks like you’re running into two separate but related issues in Azure Migrate. Here’s how you can troubleshoot each:

    1. Internal system error during assessment • Go into your Azure Migrate project → Servers, databases and web apps → Migration tools → Jobs. Find the failed assessment job and note the exact error code/message. • Common causes: – Appliance can’t fetch perf data or metadata from your source (VMware vCenter, Hyper-V host or physical server). – Credentials on the appliance don’t have the required privileges (e.g. VMware guest-operations, WinRM/SSH). – Network or firewall blocking ports: • VMware: HTTPS 443 + port 902 for performance metrics • Hyper-V/WinRM: port 5985 • Linux/SSH: port 22
      – vCenter statistics level is set too low (must be level 3 for performance data). • Remediation steps:
      1. Validate appliance → source connectivity and credentials.
      2. If VMware, bump vCenter stats to level 3 and wait up to 24 hrs for data to appear.
      3. Ensure outbound port 443 is open to Azure Migrate service URLs.
      4. Re-run (recalculate) the assessment.
    2. “Performance coverage” shows “Not applicable” • That status appears when you run a Quick (static) assessment or select a zero-day performance window. In that mode, Azure Migrate only does a config-data assessment and doesn’t collect any perf counters, so “Perf coverage” = N/A. • To get an actual perf-coverage percentage:
      1. Create or recalc the assessment with a performance-based window (for example, 7 days).
      2. Keep your VMs powered on and connected to the appliance for that full duration.
      3. Verify in the portal that each VM’s Azure Migrate connection status is Connected and that no perf counters are missing.
      4. Once the window closes, recalculate – you’ll see a % of time data was successfully collected under “Performance coverage.”

    Follow-up questions to pin it down:

    • What exact error code/message do you see in the Azure Migrate job log when the “internal error” happens?

    • Which hypervisor or server type are you assessing (VMware, Hyper-V, physical)?

    • Did you run the assessment as a Quick (0 day) assessment or choose a performance window? If the latter, how long was it?

    • Have you confirmed vCenter stats level 3 (for VMware) and that ports 443/902 (or 5985/SSH) are open in both directions?

    References

    – Troubleshoot assessment errors (missing perf data, internal errors): https://docs.microsoft.com/azure/migrate/troubleshoot-assessment
    – Common issues in creating/updating/exporting assessments:
    https://supportabilityhub.microsoft.com/solutions/apollosolutions/.../creating-updating-and-exporting-assessments
    – Azure Migrate perf-data requirements (vCenter stats level, ports): https://docs.microsoft.com/azure/migrate/troubleshoot-assessment#common-assessment-errors

    Hope this helps. Let me know if you need any assistance, thanks


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  3. MirsjerkGlobal-4608 0 Reputation points
    2026-03-04T04:32:33.1866667+00:00
    0 comments No comments

  4. SUNOJ KUMAR YELURU 18,166 Reputation points MVP Volunteer Moderator
    2026-03-04T04:02:56.9466667+00:00

    Hello @bagavan,

    The issues you’re facing with Azure Migrate can be attributed to a few common factors. For the first issue, where an internal system error occurs during assessment, it may be related to network connectivity or configuration settings. Specifically, ensure that the servers are powered on, outbound connections on port 443 are allowed, and that the Azure Migrate appliance has the necessary permissions and configurations to connect to the servers. If these conditions are not met, it can lead to errors such as Error Code: 60001: UnableToConnectToPhysicalServer, which indicates network issues or unmet prerequisites for connecting to the server.

    For the second issue regarding performance coverage showing as “Not applicable” despite successful discovery and connection, this can occur if the assessment is unable to collect the required performance data. This could be due to the servers not being profiled for the necessary duration or if there are insufficient data points available to compute the assessment. For performance-based assessments, it’s crucial to ensure that the servers are continuously monitored and that the performance data is being collected throughout the assessment period.


    If this answers your query, do click Accept Answer and Up-Vote for the same. And, if you have any further query do let us know.


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