SRE tear down script unable to remove BACKUP resource group

[dsj976]

✅ Checklist

• I have searched open and closed issues for duplicates.
• This is a problem observed when managing a Data Safe Haven.
• I can reproduce this with the latest version.
• I have read through the documentation.
• This isn't an open-ended question (open a discussion if it is).

💻 System information

• Data Safe Haven version: v4.2.0
• Operating system details: macOS Ventura 13.6.5

🌵 Powershell module versions

2024-04-18 16:31:01 [SUCCESS]: [✔] Powershell version: 7.4.1
2024-04-18 16:31:01 [SUCCESS]: [✔] Az.Automation module version: 1.9.1
2024-04-18 16:31:01 [SUCCESS]: [✔] Az.Accounts module version: 2.13.1
2024-04-18 16:31:01 [SUCCESS]: [✔] Microsoft.Graph.Applications module version: 1.21.0
2024-04-18 16:31:01 [SUCCESS]: [✔] Az.Network module version: 6.2.0
2024-04-18 16:31:01 [SUCCESS]: [✔] Az.RecoveryServices module version: 6.6.0
2024-04-18 16:31:01 [SUCCESS]: [✔] Az.Resources module version: 6.11.1
2024-04-18 16:31:01 [SUCCESS]: [✔] Az.MonitoringSolutions module version: 0.1.0
2024-04-18 16:31:01 [SUCCESS]: [✔] Powershell-Yaml module version: 0.4.2
2024-04-18 16:31:01 [SUCCESS]: [✔] Az.Dns module version: 1.1.3
2024-04-18 16:31:01 [SUCCESS]: [✔] Poshstache module version: 0.1.10
2024-04-18 16:31:01 [SUCCESS]: [✔] Az.Storage module version: 5.10.1
2024-04-18 16:31:01 [SUCCESS]: [✔] Microsoft.Graph.Authentication module version: 1.21.0
2024-04-18 16:31:01 [SUCCESS]: [✔] Az.KeyVault module version: 4.12.0
2024-04-18 16:31:01 [SUCCESS]: [✔] Microsoft.Graph.Identity.DirectoryManagement module version: 1.21.0
2024-04-18 16:31:01 [SUCCESS]: [✔] Az.Monitor module version: 4.6.0
2024-04-18 16:31:01 [SUCCESS]: [✔] Az.Compute module version: 6.3.0
2024-04-18 16:31:01 [SUCCESS]: [✔] Az.PrivateDns module version: 1.0.4
2024-04-18 16:31:01 [SUCCESS]: [✔] Az.DataProtection module version: 2.1.0
2024-04-18 16:31:01 [SUCCESS]: [✔] Microsoft.Graph.Users module version: 1.21.0
2024-04-18 16:31:01 [SUCCESS]: [✔] Az.OperationalInsights module version: 3.2.0

🚫 Describe the problem

I have noticed that the SRE teardown script (SRE_Teardown.ps1) is sometimes unable to remove the RG_SHM_<SHM-ID>_SRE_<SRE-ID>_BACKUP resource group. Re-running the script does not usually help. What is the right procedure in this situation? To manually delete the resource group in the Azure Portal?

🚂 Workarounds or solutions