Known issues with Azure SQL Managed Instance
APPLIES TO: 
Azure SQL Managed Instance
This article lists the currently known issues with Azure SQL Managed Instance, as well as their resolution date or possible workaround. To learn more about Azure SQL Managed Instance, see the overview, and what's new.
Known issues
Has workaround
Querying external table fails with not supported error message
Querying external table may fail with generic error message "Queries over external tables are not supported with the current service tier or performance level of this database. Consider upgrading the service tier or performance level of the database". The only type of external table supported in Azure SQL Managed Instance are PolyBase external tables (in preview). To allow queries on PolyBase external tables, you need to enable PolyBase on managed instance by running sp_configure command.
External tables related to Elastic Query feature of Azure SQL Database are not supported in SQL Managed Instance, but creating and querying them wasn't explicitly blocked. With support for PolyBase external tables, new checks have been introduced, blocking querying of any type of external table in managed instance unless PolyBase is enabled.
If you're using unsupported Elastic Query external tables to query data in Azure SQL Database or Azure Synapse from your managed instance, you should use Linked Server feature instead. To establish Linked Server connection from SQL Managed Instance to SQL Database, please follow instructions from this article. To establish Linked Server connection from SQL Managed Instance to SQL Synapse, check step-by-step instructions. Since configuring and testing Linked Server connection takes some time, you can use a workaround as a temporary solution to enable querying external tables related to Elastic Query feature:
Workaround: Execute the following commands (once per instance) that will enable queries on external tables:
sp_configure 'polybase enabled', 1
go
reconfigure
go
Changing the connection type does not affect connections through the failover group endpoint
If an instance participates in an auto-failover group, changing the instance's connection type doesn't take effect for the connections established through the failover group listener endpoint.
Workaround: Drop and recreate auto-failover group after changing the connection type.
Procedure sp_send_dbmail may transiently fail when @query parameter is used
Procedure sp_send_dbmail may transiently fail when @query parameter is used. When this issue occurs, every second execution of procedure sp_send_dbmail fails with error Msg 22050, Level 16, State 1 and message Failed to initialize sqlcmd library with error number -2147467259. To be able to see this error properly, the procedure should be called with default value 0 for the parameter @exclude_query_output, otherwise the error will not be propagated.
This problem is caused by a known bug related to how sp_send_dbmail is using impersonation and connection pooling.
To work around this issue wrap code for sending email into a retry logic that relies on output parameter @mailitem_id. If the execution fails, then parameter value will be NULL, indicating sp_send_dbmail should be called one more time to successfully send an email. Here is an example this retry logic.
CREATE PROCEDURE send_dbmail_with_retry AS
BEGIN
DECLARE @miid INT
EXEC msdb.dbo.sp_send_dbmail
@recipients = 'name@mail.com', @subject = 'Subject', @query = 'select * from dbo.test_table',
@profile_name ='AzureManagedInstance_dbmail_profile', @execute_query_database = 'testdb',
@mailitem_id = @miid OUTPUT
-- If sp_send_dbmail returned NULL @mailidem_id then retry sending email.
--
IF (@miid is NULL)
EXEC msdb.dbo.sp_send_dbmail
@recipients = 'name@mail.com', @subject = 'Subject', @query = 'select * from dbo.test_table',
@profile_name ='AzureManagedInstance_dbmail_profile', @execute_query_database = 'testdb',
END
Distributed transactions can be executed after removing managed instance from Server Trust Group
Server Trust Groups are used to establish trust between managed instances that is prerequisite for executing distributed transactions. After removing managed instance from Server Trust Group or deleting the group, you still might be able to execute distributed transactions. There's a workaround you can apply to be sure that distributed transactions are disabled and that is user-initiated manual failover on managed instance.
Distributed transactions cannot be executed after managed instance scaling operation
SQL Managed Instance scaling operations that include changing service tier or number of vCores will reset Server Trust Group settings on the backend and disable running distributed transactions. As a workaround, delete and create new Server Trust Group on Azure portal.
Cannot create SQL Managed Instance with the same name as logical server previously deleted
A DNS record of <name>.database.windows.com is created when you create a logical server in Azure for Azure SQL Database, and when you create a SQL Managed Instance. The DNS record must be unique. As such, if you create a logical server for SQL Database and then delete it, there's a threshold period of 7 days before the name is released from the records. In that period, a SQL Managed Instance cannot be created with the same name as the deleted logical server. As a workaround, use a different name for the SQL Managed Instance, or create a support ticket to release the logical server name.
Service Principal cannot access Azure AD and AKV
In some circumstances, there might exist an issue with Service Principal used to access Azure AD and Azure Key Vault (AKV) services. As a result, this issue impacts usage of Azure AD authentication and Transparent Database Encryption (TDE) with SQL Managed Instance. This might be experienced as an intermittent connectivity issue, or not being able to run statements such are CREATE LOGIN/USER FROM EXTERNAL PROVIDER or EXECUTE AS LOGIN/USER. Setting up TDE with customer-managed key on a new Azure SQL Managed Instance might also not work in some circumstances.
Workaround: To prevent this issue from occurring on your SQL Managed Instance before executing any update commands, or in case you have already experienced this issue after update commands, go to Azure portal, access SQL Managed Instance Active Directory admin page. Verify if you can see the error message "Managed Instance needs a Service Principal to access Azure Active Directory. Click here to create a Service Principal". In case you've encountered this error message, click on it, and follow the step-by-step instructions provided until this error have been resolved.
Limitation of manual failover via portal for failover groups
If a failover group spans across instances in different Azure subscriptions or resource groups, manual failover cannot be initiated from the primary instance in the failover group.
Workaround: Initiate failover via the portal from the geo-secondary instance.
SQL Agent roles need explicit EXECUTE permissions for non-sysadmin logins
If non-sysadmin logins are added to any SQL Agent fixed database roles, there exists an issue in which explicit EXECUTE permissions need to be granted to three stored procedures in the master database for these logins to work. If this issue is encountered, the error message "The EXECUTE permission was denied on the object <object_name> (Microsoft SQL Server, Error: 229)" will be shown.
Workaround: Once you add logins to a SQL Agent fixed database role (SQLAgentUserRole, SQLAgentReaderRole, or SQLAgentOperatorRole), for each of the logins added to these roles, execute the below T-SQL script to explicitly grant EXECUTE permissions to the stored procedures listed.
USE [master]
GO
CREATE USER [login_name] FOR LOGIN [login_name];
GO
GRANT EXECUTE ON master.dbo.xp_sqlagent_enum_jobs TO [login_name];
GRANT EXECUTE ON master.dbo.xp_sqlagent_is_starting TO [login_name];
GRANT EXECUTE ON master.dbo.xp_sqlagent_notify TO [login_name];
In-memory OLTP memory limits are not applied
The Business Critical service tier will not correctly apply max memory limits for memory-optimized objects in some cases. SQL Managed Instance may enable workload to use more memory for in-memory OLTP operations, which may affect availability and stability of the instance. In-memory OLTP queries that are reaching the limits might not fail immediately. This issue will be fixed soon. The queries that use more in-memory OLTP memory will fail sooner if they reach the limits.
Workaround: Monitor in-memory OLTP storage usage using SQL Server Management Studio to ensure that the workload is not using more than the available memory. Increase the memory limits that depend on the number of vCores, or optimize your workload to use less memory.
Wrong error returned while trying to remove a file that is not empty
SQL Server and SQL Managed Instance don't allow a user to drop a file that is not empty. If you try to remove a nonempty data file using an ALTER DATABASE REMOVE FILE statement, the error Msg 5042 – The file '<file_name>' cannot be removed because it is not empty will not be immediately returned. SQL Managed Instance will keep trying to drop the file, and the operation will fail after 30 minutes with Internal server error.
Workaround: Remove the contents of the file using the DBCC SHRINKFILE (N'<file_name>', EMPTYFILE) command. If this is the only file in the file group you would need to delete data from the table or partition associated to this file group before you shrink the file, and optionally load this data into another table/partition.
Change service tier and create instance operations are blocked by ongoing database restore
Ongoing RESTORE statement, Data Migration Service migration process, and built-in point-in-time restore will block updating a service tier or resize of the existing instance and creating new instances until the restore process finishes.
The restore process will block these operations on the managed instances and instance pools in the same subnet where the restore process is running. The instances in instance pools are not affected. Create or change service tier operations will not fail or time out. They will proceed once the restore process is completed or canceled.
Workaround: Wait until the restore process finishes, or cancel the restore process if the creation or update-service-tier operation has higher priority.
Resource Governor on Business Critical service tier might need to be reconfigured after failover
The Resource Governor feature that enables you to limit the resources assigned to the user workload might incorrectly classify some user workload after failover or a user-initiated change of service tier (for example, the change of max vCore or max instance storage size).
Workaround: Run ALTER RESOURCE GOVERNOR RECONFIGURE periodically or as part of a SQL Agent job that executes the SQL task when the instance starts if you are using
Resource Governor.
Cross-database Service Broker dialogs must be reinitialized after service tier upgrade
Cross-database Service Broker dialogs will stop delivering the messages to the services in other databases after change service tier operation. The messages are not lost, and they can be found in the sender queue. Any change of vCores or instance storage size in SQL Managed Instance will cause a service_broke_guid value in sys.databases view to be changed for all databases. Any DIALOG created using a BEGIN DIALOG statement that references Service Brokers in other database will stop delivering messages to the target service.
Workaround: Stop any activity that uses cross-database Service Broker dialog conversations before updating a service tier, and reinitialize them afterward. If there are remaining messages that are undelivered after a service tier change, read the messages from the source queue and resend them to the target queue.
Temporary database is used during RESTORE operation
When a database is restoring in SQL Managed Instance, the restore service will first create an empty database with the desired name to allocate the name on the instance. After some time, this database will be dropped, and restoring of the actual database will be started.
The database that is in Restoring state will temporarily have a random GUID value instead of name. The temporary name will be changed to the desired name specified in the RESTORE statement once the restore process finishes.
In the initial phase, a user can access the empty database and even create tables or load data in this database. This temporary database will be dropped when the restore service starts the second phase.
Workaround: Do not access the database that you are restoring until you see that restore is completed.
Exceeding storage space with small database files
CREATE DATABASE, ALTER DATABASE ADD FILE, and RESTORE DATABASE statements might fail because the instance can reach the Azure Storage limit.
Each General Purpose instance of SQL Managed Instance has up to 35 TB of storage reserved for Azure Premium Disk space. Each database file is placed on a separate physical disk. Disk sizes can be 128 GB, 256 GB, 512 GB, 1 TB, or 4 TB. Unused space on the disk isn't charged, but the total sum of Azure Premium Disk sizes can't exceed 35 TB. In some cases, a managed instance that doesn't need 8 TB in total might exceed the 35 TB Azure limit on storage size due to internal fragmentation.
For example, a General Purpose instance of SQL Managed Instance might have one large file that's 1.2 TB in size placed on a 4-TB disk. It also might have 248 files that are 1 GB each and that are placed on separate 128-GB disks. In this example:
- The total allocated disk storage size is 1 x 4 TB + 248 x 128 GB = 35 TB.
- The total reserved space for databases on the instance is 1 x 1.2 TB + 248 x 1 GB = 1.4 TB.
This example illustrates that under certain circumstances, due to a specific distribution of files, an instance of SQL Managed Instance might reach the 35-TB limit that's reserved for an attached Azure Premium Disk when you might not expect it to.
In this example, existing databases continue to work and can grow without any problem as long as new files aren't added. New databases can't be created or restored because there isn't enough space for new disk drives, even if the total size of all databases doesn't reach the instance size limit. The error that's returned in that case isn't clear.
You can identify the number of remaining files by using system views. If you reach this limit, try to empty and delete some of the smaller files by using the DBCC SHRINKFILE statement or switch to the Business Critical tier, which doesn't have this limit.
GUID values shown instead of database names
Several system views, performance counters, error messages, XEvents, and error log entries display GUID database identifiers instead of the actual database names. Don't rely on these GUID identifiers because they're replaced with actual database names in the future.
Workaround: Use sys.databases view to resolve the actual database name from the physical database name, specified in the form of GUID database identifiers:
SELECT name as ActualDatabaseName, physical_database_name as GUIDDatabaseIdentifier
FROM sys.databases
WHERE database_id > 4;
Transaction scope on two databases within the same instance isn't supported
(Resolved in March 2020) The TransactionScope class in .NET doesn't work if two queries are sent to two databases within the same instance under the same transaction scope:
using (var scope = new TransactionScope())
{
using (var conn1 = new SqlConnection("Server=quickstartbmi.neu15011648751ff.database.windows.net;Database=b;User ID=myuser;Password=mypassword;Encrypt=true"))
{
conn1.Open();
SqlCommand cmd1 = conn1.CreateCommand();
cmd1.CommandText = string.Format("insert into T1 values(1)");
cmd1.ExecuteNonQuery();
}
using (var conn2 = new SqlConnection("Server=quickstartbmi.neu15011648751ff.database.windows.net;Database=b;User ID=myuser;Password=mypassword;Encrypt=true"))
{
conn2.Open();
var cmd2 = conn2.CreateCommand();
cmd2.CommandText = string.Format("insert into b.dbo.T2 values(2)"); cmd2.ExecuteNonQuery();
}
scope.Complete();
}
Workaround (not needed since March 2020): Use SqlConnection.ChangeDatabase(String) to use another database in a connection context instead of using two connections.
CLR modules and linked servers sometimes can't reference a local IP address
CLR modules in SQL Managed Instance and linked servers or distributed queries that reference a current instance sometimes can't resolve the IP of a local instance. This error is a transient issue.
Transaction scope on two databases within the same instance isn't supported
(Resolved in March 2020) The TransactionScope class in .NET doesn't work if two queries are sent to two databases within the same instance under the same transaction scope:
using (var scope = new TransactionScope())
{
using (var conn1 = new SqlConnection("Server=quickstartbmi.neu15011648751ff.database.windows.net;Database=b;User ID=myuser;Password=mypassword;Encrypt=true"))
{
conn1.Open();
SqlCommand cmd1 = conn1.CreateCommand();
cmd1.CommandText = string.Format("insert into T1 values(1)");
cmd1.ExecuteNonQuery();
}
using (var conn2 = new SqlConnection("Server=quickstartbmi.neu15011648751ff.database.windows.net;Database=b;User ID=myuser;Password=mypassword;Encrypt=true"))
{
conn2.Open();
var cmd2 = conn2.CreateCommand();
cmd2.CommandText = string.Format("insert into b.dbo.T2 values(2)"); cmd2.ExecuteNonQuery();
}
scope.Complete();
}
Workaround (not needed since March 2020): Use SqlConnection.ChangeDatabase(String) to use another database in a connection context instead of using two connections.
No resolution
Azure AD logins and users are not supported in SSDT
SQL Server Data Tools don't fully support Azure AD logins and users.
Impersonation of Azure AD login types is not supported
Impersonation using EXECUTE AS USER or EXECUTE AS LOGIN of the following Azure Active Directory (Azure AD) principals is not supported:
- Aliased Azure AD users. The following error is returned in this case:
15517. - Azure AD logins and users based on Azure AD applications or service principals. The following errors are returned in this case:
15517and15406.
Transactional Replication must be reconfigured after geo-failover
If Transactional Replication is enabled on a database in an auto-failover group, the SQL Managed Instance administrator must clean up all publications on the old primary and reconfigure them on the new primary after a failover to another region occurs. For more information, see Replication.
TEMPDB structure and content is re-created
The tempdb database is always split into 12 data files, and the file structure cannot be changed. The maximum size per file can't be changed, and new files cannot be added to tempdb. Tempdb is always re-created as an empty database when the instance starts or fails over, and any changes made in tempdb will not be preserved.
Error logs aren't persisted
Error logs that are available in SQL Managed Instance aren't persisted, and their size isn't included in the maximum storage limit. Error logs might be automatically erased if failover occurs. There might be gaps in the error log history because SQL Managed Instance was moved several times on several virtual machines.
Resolved
When using SQL Server authentication, usernames with '@' are not supported
Usernames that contain the '@' symbol in the middle (e.g. 'abc@xy') are not able to log in using SQL Server authentication.
Restoring manual backup without CHECKSUM might fail
In certain circumstances manual backup of databases that was made on a managed instance without CHECKSUM might fail to be restored. In such cases, retry restoring the backup until you're successful.
Workaround: Take manual backups of databases on managed instances with CHECKSUM enabled.
Agent becomes unresponsive upon modifying, disabling, or enabling existing jobs
In certain circumstances, modifying, disabling, or enabling an existing job can cause the agent to become unresponsive. The issue is automatically mitigated upon detection, resulting in a restart of the agent process.
Permissions on resource group not applied to SQL Managed Instance
When the SQL Managed Instance Contributor Azure role is applied to a resource group (RG), it's not applied to SQL Managed Instance and has no effect.
Workaround: Set up a SQL Managed Instance Contributor role for users at the subscription level.
SQL Agent jobs can be interrupted by Agent process restart
(Resolved in March 2020) SQL Agent creates a new session each time a job is started, gradually increasing memory consumption. To avoid hitting the internal memory limit, which would block execution of scheduled jobs, Agent process will be restarted once its memory consumption reaches threshold. It may result in interrupting execution of jobs running at the moment of restart.
@query parameter not supported in sp_send_db_mail
The @query parameter in the sp_send_db_mail procedure doesn't work.
Misleading error message on Azure portal suggesting recreation of the Service Principal
Active Directory admin blade of Azure portal for Azure SQL Managed Instance may be showing the following error message even though Service Principal already exists:
"Managed Instance needs a Service Principal to access Azure Active Directory. Click here to create a Service Principal"
You can neglect this error message if Service Principal for the managed instance already exists, and/or Azure Active Directory authentication on the managed instance works.
To check whether Service Principal exists, navigate to the Enterprise applications page on the Azure portal, choose Managed Identities from the Application type dropdown list, select Apply and type the name of the managed instance in the search box. If the instance name shows up in the result list, Service Principal already exists and no further actions are needed.
If you already followed the instructions from the error message and clicked the link from the error message, Service Principal of the managed instance has been recreated. In that case, please assign Azure AD read permissions to the newly created Service Principal in order for Azure AD authentication to work properly. This can be done via Azure PowerShell by following instructions.
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Next steps
For a list of SQL Managed Instance updates and improvements, see SQL Managed Instance service updates.
For updates and improvements to all Azure services, see Service updates.
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