Here are the step by step process to upgrade SQL Server to the latest version:
https://docs.microsoft.com/en-us/sql/database-engine/install-windows/upgrade-sql-server-using-the-installation-wizard-setup?view=sql-server-2017

The reason of getting SQL error 8992 could be many. Check out various possible reasons of getting this error and step by step process to fix it.

Here are the step by step process to troubleshoot SQL Server error 8921:
https://www.systoolsgroup.com/updates/troubleshoot-sql-server-error-8921-error-8967/

The reason of getting error 5120 is that MDF file are not located at their accurate location. It might be the possibility that system drives might not be having permission...

This may help you out:
https://dba.stackexchange.com/questions/80507/issues-with-module-signing-and-ssis-catalog-internal-procedures

Have a look at this:
https://blog.sqlauthority.com/2014/11/13/sql-server-fix-msg-4864-level-16-state-1-bulk-load-data-conversion-error/
This may help you out.

The error occurs due to many reasons like defects in hardware, virus attack, or re-installation in SQL Server. You can run DBCC CHECKDB to determine the cause of the error....

SQL Error 233 causes while accessing the database, sometimes user faces the situation when they log in into SQL Server Authentication mode, and it display error message 233. This may...

\TestAccount cannot be used for a SQL login name as \ is not allowed. SQL Server authentication on the General page when you create a new login

Here is the difference between truncating and shrinking the log file in SQL Server. 
https://www.systoolsgroup.com/updates/difference-between-truncating-and-shrinking-the-log-file/

The issue occurs due to the subquery of msdb.dbo.sp_sqlagent_get_perf_counters system stored procedure calculates value of counter incorrectly. The subquery lacks an inner join relationship for the column in condition of...

The reason of getting Login failed error could be many, either your username or password is incorrect or your instance of SQL Server or password for login has expired. Here...

This may help you out:
https://www.sqlserverlogexplorer.com/resolve-microsoft-sql-server-error-823/

This may help you out:
https://community.helpsystems.com/knowledge-base/rjs/rpg2sql-integrator/sql-server-error-18452-not-associated-trusted-sql-server-connection/

You should rebuild indexes often enough so that production is not detrimentally affected by index degradation. You can You should reorganize your indices as soon as index fragmentation reaches more...