-25008: Logon failure; previous user's (<user_name>) connection was restored 

Explanation:

An error occurred when a database user attempted to log on to the database instance. The last database user who was successfully logged on has been logged on again.

This error message only appears if a new database user is unable log on to a database instance after another database user has already been logged on and after processing of export and import commands. This message precedes the error message –25005.

User Response:

Since this message merely informs you that a previous connection has been restored, proceed as described in error message -25005.