A database connection could not be established

[Raul Alberto Rueda Barajas]

Yesterday the server was working fine with the 4.3.2 version and a sql express 2014, 
now any time I try to enter in my server they display a form setup like it was a new 
instance and when I try to enter the setup values the sever return me this error.

<Sory for my english>

The configuration entered is not valid. A database connection could not be established. 
Please check your configuration and try again.

The configuration entered is not valid. A database connection could not be established. 
Please check your configuration and try again.
	com.atlassian.stash.internal.db.DefaultDatabaseManager.validateConfiguration(DefaultDatabaseManager.java:230)
	com.atlassian.stash.internal.migration.DefaultMigrationService.validateConfiguration(DefaultMigrationService.java:85)
	sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	...
Could not get JDBC Connection; nested exception is com.microsoft.sqlserver.jdbc.SQLServerException: 
No se pudo realizar la conexión TCP/IP al host SRV17-WEB, puerto 1433. Error: "connect timed out. 
Verifique las propiedades de conexión, compruebe que hay una instancia de SQL Server ejecutándose en el host y 
aceptando las conexiones TCP/IP en el puerto y compruebe que no hay ningún firewall bloqueando las conexiones 
TCP en el puerto.".
	org.springframework.jdbc.datasource.DataSourceUtils.getConnection(DataSourceUtils.java:80)
	com.atlassian.stash.internal.db.DefaultDatabaseValidator.validate(DefaultDatabaseValidator.java:44)
	com.atlassian.stash.internal.db.DefaultDatabaseManager.validateConfiguration(DefaultDatabaseManager.java:227)
	...
No se pudo realizar la conexión TCP/IP al host SRV17-WEB, puerto 1433. Error: "connect timed out. Verifique las 
propiedades de conexión, compruebe que hay una instancia de SQL Server ejecutándose en el host y aceptando las 
conexiones TCP/IP en el puerto y compruebe que no hay ningún firewall bloqueando las conexiones TCP en el puerto.".
	com.microsoft.sqlserver.jdbc.SQLServerException.makeFromDriverError(SQLServerException.java:191)
	com.microsoft.sqlserver.jdbc.SQLServerException.ConvertConnectExceptionToSQLServerException(SQLServerException.java:242)
	com.microsoft.sqlserver.jdbc.SocketFinder.findSocket(IOBuffer.java:2280)
	...

[Nic Brough -Adaptavist-]

I'm afraid that really is what the error message said - it's trying to reach the database over your network, and it can't.  Check the network and the database server is running and accepting connections.