This document describes how to troubleshoot Microsoft SQL Server running on Linux or in a Docker container. When troubleshooting SQL Server on Linux, please remember to review the supported features and known limitations in the SQL Server on Linux Release Notes.
Troubleshoot connection failures
If you are having difficulty connecting to your Linux SQL Server, there are a few things to check.
Verify that the server name or IP address is reachable from your client machine.
To find the IP address of your Ubuntu machine, you can run the ifconfig command as in the following example:
sudo ifconfig eth0 | grep 'inet addr'
For Red Hat, you can use the ip addr as in the following example:
sudo ip addr show eth0 | grep "inet"
One exception to this technique relates to Azure VMs. For Azure VMs, find the public IP for the VM in the Azure portal.
If applicable, check that you have opened the SQL Server port (default 1433) on the firewall.
For Azure VMs, check that you have a network security group rule for the default SQL Server port.
Verify that the user name and password do not contain any typos or extra spaces or incorrect casing.
Try to explicitly set the protocol and port number with the server name like the following: tcp:servername,1433.
Network connectivity issues can also cause connection errors and timeouts. After verifying your connection information and network connectivity, try the connection again.
Manage the SQL Server service
The following sections show how to start, stop, restart, and check the status of the SQL Server service.
Manage the mssql-server service in Red Hat Enterprise Linux (RHEL) and Ubuntu
Check the status of the status of the SQL Server service using this command:
sudo systemctl status mssql-server
You can stop, start, or restart the SQL Server service as needed using the following commands:
sudo systemctl stop mssql-server sudo systemctl start mssql-server sudo systemctl restart mssql-server
Manage the execution of the mssql Docker container
You can get the status and container ID of the latest created SQL Server Docker container by running the following command (The ID will be under the “CONTAINER ID” column):
sudo docker ps -l
You can stop or restart the SQL Server service as needed using the following commands:
sudo docker stop <container ID> sudo docker restart <container ID>
For more troubleshooting tips for Docker, see Troubleshooting SQL Server Docker containers.
Access the log files
The SQL Server engine logs to the /var/opt/mssql/log/errorlog file in both the Linux and Docker installations. You need to be in ‘superuser’ mode to browse this directory.
The installer logs here: /var/opt/mssql/setup-< time stamp representing time of install> You can browse the errorlog files with any UTF-16 compatible tool like ‘vim’ or ‘cat’ like this:
sudo cat errorlog
If you prefer, you can also convert the files to UTF-8 to read them with ‘more’ or ‘less’ with the following command:
sudo iconv –f UTF-16LE –t UTF-8 <errorlog> -o <output errorlog file>
Extended events can be queried via a SQL command. More information about extended events can be found here:
Look for dumps in the log directory in Linux. Check under the /var/opt/mssql/log directory for Linux Core dumps (.tar.gz2 extension) or SQL minidumps (.mdmp extension)
For Core dumps
sudo ls /var/opt/mssql/log | grep .tar.gz2
For SQL dumps
sudo ls /var/opt/mssql/log | grep .mdmp
You can not connect to your remote SQL Server instance.
See the troubleshooting section of the topic, Connect to SQL Server on Linux.
ERROR: Hostname must be 15 characters or less.
This is a known-issue that happens whenever the name of the machine that is trying to install the SQL Server Debian package is longer than 15 characters. There are currently no workarounds other than changing the name of the machine. One way to achieve this is by editing the hostname file and rebooting the machine. The following website guide explains this in detail.
Resetting the system administration (SA) password.
If you have forgotten the system administrator (SA) password or need to reset it for some other reason please follow these steps.
Following these steps will stop the SQL Server service temporarily.
Log into the host terminal, run the following commands and follow the prompts to reset the SA password:
sudo systemctl stop mssql-server sudo /opt/mssql/bin/mssql-conf setup
Using special characters in password.
If you use some characters in the SQL Server login password you may need to escape them when using them in the Linux terminal. You will need to escape the $ anytime using the backslash character you are using it in a terminal command/shell script:
Does not work:
sudo sqlcmd -S myserver -U sa -P Test$$
sqlcmd -S myserver -U sa -P Test\$\$
Support is available through the community and monitored by the engineering team. For specific questions, use the following resources: