5.4 About Blocked Connection Requests

Blocked connection requests can occur when an incoming request occurs before the respective instance has been registered, or when a database is in restricted mode, such as when a shutdown of the database is in progress. If a database instance is in restricted mode, then LREG instructs the listener to block all connections to the instance. Clients attempting to connect receive one of the following errors:

• ORA-12526: TNS:listener: all appropriate instances are in restricted mode

• ORA-12527: TNS:listener: all appropriate instances are in restricted mode or blocking new connections

• ORA-12528: TNS:listener: all appropriate instances are blocking new connections

The ORA-12528 error occurs when a database instance is not yet registered with the listener.

See Also:

• Oracle Database Error Messages for information about these error messages

• Oracle Database SQL Reference for information about the ALTER SYSTEM REGISTER statement

• Oracle XML DB Developer's Guide for information about dynamically registering HTTP, FTP, and WebDAV listening endpoints