How to Downgrade Azure Database for MySQL Flexible Server Back to Burstable Tier After Major Version Upgrade

When performing a Major Version Upgrade (MVU) on Azure Database for MySQL Flexible Server, many users notice their server automatically shifts from a Burstable SKU (e.g., Standard_B1ms) to a General Purpose SKU (such as Standard_D2ads_v5).

While Microsoft states it should be possible to downgrade back to Burstable, some users encounter this error when trying:

az mysql flexible-server update \
  --resource-group rg-XXXX-XXXX \
  --name mysql-XXXX-XXXXX \
  --tier Burstable \
  --sku-name Standard_B1ms

Error:

Incorrect value for --sku-name. The SKU name does not match tier selection.
Allowed values for given tier: set()

This usually means no Burstable SKUs are being offered for your current server configuration. Let’s go step by step.

Why This Happens

1. Temporary SKU upgrade: During MVU, Burstable servers are moved to General Purpose for resource consistency.
2. Feature limitations: Burstable tier doesn’t support Zone-Redundant High Availability (ZR-HA). If enabled, you cannot revert.
3. SKU restrictions: After MVU, B1ms is often not offered anymore, but B2s may still be available.
4. CLI bug: At times, the Azure CLI returns an empty SKU list, causing the command to fail even when Burstable exists.
5. Server state: Some compute changes are blocked when the server is Stopped.

See also: How to Fix Azure OpenAI Resource Blocked Error Due to Content Policy

Step 1: Check High Availability

Run:

az mysql flexible-server show \
  --resource-group rg-XXXX-XXXX \
  --name mysql-XXXX-XXXXX \
  --query highAvailability

• If zoneRedundant = true → Burstable is not supported. You will need to migrate.
• If HA is Disabled or SameZone → downgrade is possible.

Step 2: Verify Available SKUs in Your Region

Before retrying, list the SKUs:

az mysql flexible-server list-skus --location eastus --output table

• Look for Standard_B2s (most commonly available).
• If Burstable SKUs don’t appear, capacity may be unavailable in your region.

Step 3: Attempt Downgrade to B2s

Since B1ms is often blocked after MVU, try:

az mysql flexible-server update \
  --resource-group rg-XXXX-XXXX \
  --name mysql-XXXX-XXXXX \
  --tier Burstable \
  --sku-name Standard_B2s

If successful, your server is now back on Burstable.

Step 4: Use Azure Portal (GUI Method)

If CLI continues to fail:

1. Go to Azure Portal → MySQL Flexible Server → Compute + Storage.
2. Select Change Compute Tier.
3. Choose Burstable → Standard_B2s (if available).
4. Save changes.

Note: Some users report the Portal succeeds even when CLI rejects the SKU.

Step 5: If Burstable Still Isn’t Offered

If Burstable SKUs are unavailable for your server/region, or HA prevents downgrade, you must migrate to a new Burstable server.

Migration Checklist

• Create a new Flexible Server
  • Region: same (East US) or nearby (East US 2).
  • SKU: Standard_B2s.
  • Disable Zone-Redundant HA if you need Burstable.
• Backup or Dump Your Database
  • Using

mysqldump -h oldserver.mysql.database.azure.com -u user@oldserver -p dbname > backup.sql

• Restore into the New Server

mysql -h newserver.mysql.database.azure.com -u user@newserver -p dbname < backup.sql

• Update Application Connection Strings
  • Switch your app’s DB endpoint to the new server’s hostname.
• Test and Decommission Old Server
  • Validate queries and workload.
  • Delete the General Purpose server once migration is stable.

Step 6: Open Microsoft Support Ticket

If:

• Your server has no HA,
• Burstable SKUs exist in your region,
• But the CLI/Portal still shows empty SKU sets,

→ Open a support request.

• Include the CLI error output.
• Provide Activity Log correlation ID.
• Mention the post-MVU SKU listing bug in Flexible Server.

Performance Consideration

Downgrading from General Purpose to Burstable (B2s) can significantly reduce performance.

• Burstable is only suited for light workloads or development/test environments.
• If your app handled production load on General Purpose, monitor CPU credits carefully after downgrade.

Downgrading an Azure Database for MySQL Flexible Server back to the Burstable tier after a Major Version Upgrade can be tricky, but it is possible with the right approach. The most common blockers are zone-redundant high availability, which is not supported on Burstable servers, and the fact that B1ms is no longer offered after MVU, making B2s the realistic option.

In many cases, the Azure Portal succeeds where CLI commands fail due to SKU listing issues. If Burstable is not available in your region, migration to a new Burstable server remains the safest fallback. And if you encounter the empty SKU set error, raising a support ticket is the best way to resolve it.