Update
The issue was irrelevant to which type of linked service type was selected. I could reproduce the issue by disabling the Managed identities (MI) feature for the Azure Data Factory resource, which resulted in the lack of service principal to authenticate access to Azure Key Vault secrets on behalf of the SQL server linked service. Hence even given the linked service type of SQL Server, the issue was also reproducible, when the Azure Data Factory Instance was not enabled with MI.
Please enable the MI feature for your qa instance by navigating to this Azure Data Factory resource under your subscription in Azure Portal following the steps in the image below.
Since it will generate a new service principal (system assigned MI) in your AAD, please also grant the MI with the required permission according to your need to retrieve secrets from the Azure Key Vault.
Once the above steps were completed, the linked service of SQL server was able to authenticate against the system assigned MI to access the Azure Key Vault and proceed to list secrets with different versions.
I could only reproduce the issue when the System Assigned managed identity of the target ADF instance was disabled. After the ARM template deployment via Azure DevOps pipeline completed successfully, I could see the entities like linked services, pipelines and triggers were published. However, when clicking on the Test connection button of my linked service of AzureSqlDatabase1, I encountered the error in the screenshot below.
To fix the issue, I navigated to the target ADF resource under my subscription in Azure Portal and enabled the System assigned managed Identity for it. Since it will create a new enterprise app in your AAD, please grant the new service principle with required permissions to access your linked services.
devtoqa, there should be no error during deployment, right? Have you tested to deploy the same templates via Azure Portal or Azure CLI to see if the issue is reproducible? It is helpful for us to narrow down the cause of the issue. Thx.AzureKeyVault1link service in your screenshot, right? From the error message itself, it seemed yourqaADF instance hadn't enabled Managed Identity. May I know if yourdevandqaenvironments are two ADF instances? If yes, you may navigate to theqaADF resource under your Azure Subscription in Azure Portal -> select the Settings section and Managed identities blade -> check if the System assgined managed identity status is turned On.