There may be some reasons you can eliminate them bit by bit
1. No user assigned a user to him (can have administrator privileges) and serve
Find the corresponding sql service in it: Computer --> Management --> Services and Applications --> Services -->
sqln server agent ---->right-click properties -->Login -->Select account and enter password, click OK after applying
2. Enter the SQL Configuration Manager SQL Server Network Configuration
1) mssql server protocol --->VIA disabled
2) sqlexpress protocol --->VIA disabled
SQL Native Client10.0 Configuration --->Right-click properties --> Forced protocol encryption to select No
3. Log in to the database ---->Security ----->Login name --->Enable NT AUTHORITY\SYSTEM, NT SERVICE\MSSQLSERVER, NT SERVER\SQLEXPVERAGENT and other system default accounts
Hope it helps you.
1. No user assigned a user to him (can have administrator privileges) and serve
Find the corresponding sql service in it: Computer --> Management --> Services and Applications --> Services -->
sqln server agent ---->right-click properties -->Login -->Select account and enter password, click OK after applying
2. Enter the SQL Configuration Manager SQL Server Network Configuration
1) mssql server protocol --->VIA disabled
2) sqlexpress protocol --->VIA disabled
SQL Native Client10.0 Configuration --->Right-click properties --> Forced protocol encryption to select No
3. Log in to the database ---->Security ----->Login name --->Enable NT AUTHORITY\SYSTEM, NT SERVICE\MSSQLSERVER, NT SERVER\SQLEXPVERAGENT and other system default accounts
Hope it helps you.