Azure DocumentDB cluster stuck in Updating and unreachable for more than 4 hours

Question

Azure DocumentDB cluster stuck in Updating and unreachable for more than 4 hours

Yanbin Gao 20

The production Azure DocumentDB MongoDB vCore cluster was working on M10. Immediately after scaling from M10 to M20, MongoDB connectivity stopped. DNS/SRV resolution works, public access is enabled, firewall is 0.0.0.0/0, there are no private endpoints, but TCP connection to the resolved MongoDB endpoint on port 10260 times out from both an external Mac and an Azure App Service. I then attempted to scale back from M20 to M10, and the cluster has now remained in Updating for over 4 hours.

Himaja Y 375 Reputation points Microsoft External Staff Moderator

2026-09-03T10:49:40.15+00:00

Hi @Yanbin Gao ,

Thank you for the patience.

After reviewing the issue from the backend, we found that the VM was being scaled up to the B2ms SKU, which is currently not supported in the target environment due to capacity constraints. Although the scale-up operation completed successfully, the VM could not boot with the B2ms SKU because the required capacity was unavailable. As a mitigation, we reverted the VM to the previously working B1ms SKU, which allowed the VM to start successfully and restored the cluster to a healthy state.
Himaja Y 375 Reputation points Microsoft External Staff Moderator

2026-09-04T10:55:19.31+00:00

Hi @Yanbin Gao ,

Just checking in to see if the information provided earlier was helpful. Please let us know if you need any additional details or assistance, and we’ll gladly continue supporting you.
Yanbin Gao 20 Reputation points

2026-09-04T17:37:56.2466667+00:00

Hi Himaja,

What I saw were different. after couple of days of works on your side, the cluster can be accessed. the status was ready and I can connect to it and the cluster tier was M20. as I already resolved the issue myself, I downgraded it to M10.

I successfuly tested on my other cluster and proved that I can scale a claster up to M20. I tested several time, it worked. I deleted the cluster with this issue and restored it to a different cluster and delete the issue one.

But anyway, thank you for your support and make my db accessable.

Best regards,

Answer accepted by question author

0 additional answers

Your answer

Himaja Y 375 Reputation points Microsoft External Staff Moderator

2026-09-03T10:49:40.15+00:00

Hi @Yanbin Gao ,

Thank you for the patience.

After reviewing the issue from the backend, we found that the VM was being scaled up to the B2ms SKU, which is currently not supported in the target environment due to capacity constraints. Although the scale-up operation completed successfully, the VM could not boot with the B2ms SKU because the required capacity was unavailable. As a mitigation, we reverted the VM to the previously working B1ms SKU, which allowed the VM to start successfully and restored the cluster to a healthy state.
Himaja Y 375 Reputation points Microsoft External Staff Moderator

2026-09-04T10:55:19.31+00:00

Hi @Yanbin Gao ,

Just checking in to see if the information provided earlier was helpful. Please let us know if you need any additional details or assistance, and we’ll gladly continue supporting you.
Yanbin Gao 20 Reputation points

2026-09-04T17:37:56.2466667+00:00

Hi Himaja,

What I saw were different. after couple of days of works on your side, the cluster can be accessed. the status was ready and I can connect to it and the cluster tier was M20. as I already resolved the issue myself, I downgraded it to M10.

I successfuly tested on my other cluster and proved that I can scale a claster up to M20. I tested several time, it worked. I deleted the cluster with this issue and restored it to a different cluster and delete the issue one.

But anyway, thank you for your support and make my db accessable.

Best regards,

Answer 1

Hi @Yanbin Gao ,

Thank you for reaching out to the Microsoft Q&A forum.

Based on your description, this appears to be related to the scaling operation rather than a networking configuration issue.

Since:

The cluster was working normally on M10
Connectivity stopped immediately after scaling to M20
DNS/SRV resolution is successful
Public access is enabled and firewall rules allow all IPs
The issue occurs from both external clients and Azure services
The cluster has been stuck in Updating for more than 4 hours

This suggests the cluster may be stuck in an intermediate provisioning state after the scale operation. Similar Azure Cosmos DB cases have required backend investigation when resources remain in an Updating state indefinitely.

Recommended checks:

Review the Activity Log for any failed scale or provisioning operations.
Check Resource Health for any platform-related issues.

Verify the current provisioning state using Azure CLI:

   az cosmosdb mongocluster show \
    --resource-group <resource-group> \
    --name <cluster-name>

Avoid initiating additional scale operations while the cluster remains in the Updating state.

If the cluster continues to be unavailable, could you please share the requested details via private chat to help us investigate this issue further?

And also, please share the Approximate time when the scale operation started,cluster region and any Activity Log errors if available, and we can assist further.