You can upgrade a Microsoft SQL Server Express instance using the SQL Server Express installation wizard.
The version of SQL Server Express delivered with ArcGIS has changed over time. The following lists the version of SQL Server Express delivered with each version of ArcGIS:
- ArcGIS 9.2: SQL Server 2005 Express Service Pack (SP) 2
- ArcGIS 9.3: SQL Server 2005 Express with Advanced Services
- ArcGIS 9.3.1 and 10: SQL Server 2008 SP1 Express with Advanced Services
- ArcGIS 10.1 through 10.2.2: SQL Server 2008 R2 Express with Advanced Services
- ArcGIS 10.3 through 10.4.1: SQL Server 2012 Express
- ArcGIS 10.5 through 10.7.1: SQL Server 2014 Express
- ArcGIS 10.8.x: SQL Server 2017 Express
A SQL Server setup wizard is provided as part of the database server installation files you download from My Esri. You have the option to run the SQL Server installation included with this setup to upgrade your existing instance (database server). Or you can obtain a supported version of SQL Server Express from Microsoft and run it to upgrade your instance.
See Microsoft documentation for instructions on upgrading SQL Server.
Before you upgrade, be sure to create backups of all your geodatabases.