Azure Bastion Developer SKU: Unable to connect to any VM due to "Internal server error while requesting session"

Service: Azure Bastion (Developer SKU), Windows VMs, UK South

Scenario: Connect to Windows VMs over RDP via Azure Portal → Connect → Bastion (VM password auth). This worked until 14 Oct 2026.

Result: A few seconds after clicking Connect: "There was an error in requesting a session. Please try again. Internal server error while requesting session." No connection attempt reaches the VM (no logon events on the target).

Environment:

• 2 Developer Bastion hosts in 2 different subscriptions, same error on both
• Multiple users, each on a different network
• Last successful session: 14 Oct 2026, 07:55 UTC

Troubleshooting done:

• Clean browser profile, all extensions disabled: same error
• Deleted and recreated the Bastion host: provisioning Succeeded, same error
• Target VMs: running, VM agent Ready, RDP listening on 3389, NSG allows 3389 from VirtualNetwork, no changes in 30 days
• Service Health: no Bastion events; Resource Health: "Unknown"

Steps to reproduce:

1. Azure Portal → VM → Connect → Bastion
2. Authentication type: VM Password, enter username/password
3. Click Connect → after a few seconds the error above is shown

Question: Is there a known issue with Bastion Developer SKU in UK South, and is there a workaround other than upgrading to Basic SKU?