I am facing issue while connecting bitbucket to external database oracle 11g.

[Sushil Swain]

[http-nio-7990-exec-7] @12VXA4Ax1048x72x0 9dgega 0:0:0:0:0:0:0:1 "POST /setup HTTP/1.1" c.a.s.i.db.DefaultDatabaseManager A connection could not be opened with the DataSource

org.springframework.jdbc.CannotGetJdbcConnectionException: Could not get JDBC Connection; nested exception is java.sql.SQLRecoverableException: Listener refused the connection with the following error:

ORA-12514, TNS:listener does not currently know of service requested in connect descriptor
 
        at org.springframework.jdbc.datasource.DataSourceUtils.getConnection(DataSourceUtils.java:80)
        at com.atlassian.stash.internal.db.DefaultDatabaseValidator.validate(DefaultDatabaseValidator.java:44)

[Nic Brough -Adaptavist-]

This is what it says it is - it can't connect to the database, because the database server does not appear to be there. 

The TNS error is telling you that TNS is not set up to route to that database, (or possibly allow connections), so you need to fix that and try again.