ORA-12520 TNS:listener could not find available handler for requested type of server
This is an Oracle Database Server Message. This can be generated by the Oracle Database when running any Oracle program.
None of the known and available service handlers for requested type of server (dedicated or shared) are appropriate for the client connection.
Run "lsnrctl services" to ensure that the instance(s) have registered with the listener and that the appropriate handlers are accepting connections.
Contacting Oracle support services ?
Some messages recommend contacting Oracle Support Services to report a problem. When you contact Oracle Support Services, please have the following information available:
- The hardware, operating system, and release number of the operating system on which Oracle is running
- The complete release number of the Oracle Database (for example, release 22.214.171.124.0 or release 126.96.36.199.2)
- All Oracle programs (with version numbers) in use when the error occurred. For example, SQL*Net V2.0 or SQL*Forms V3.0
- If you encountered one or more error codes or messages, then the exact code numbers and message text, in the order they appeared
- The problem severity, according to the following codes:
- Program not usable. Critical impact on operations.
- Program usable. Operations severely restricted.
- Program usable with limited functions. Not critical to overall operations.
- Problem circumvented by customer. Minimal effect, if any, on operations.
- Your name
- The name of your organization
- Your Oracle Support ID Number
- Your telephone number
Linked Error Messages
- ORA-12513 TNS:service handler found but it has registered for a different protocol
- ORA-12514 TNS:listener does not currently know of service requested in connect descriptor
- ORA-12515 TNS:listener could not find a handler for this presentation
- ORA-12516 TNS:listener could not find available handler with matching protocol stack
- ORA-12518 TNS:listener could not hand off client connection
- ORA-12519 TNS:no appropriate service handler found
- ORA-12521 TNS:listener does not currently know of instance requested in connect descriptor
- ORA-12522 TNS:listener could not find available instance with given INSTANCE_ROLE
- ORA-12523 TNS:listener could not find instance appropriate for the client connection
- ORA-12524 TNS:listener could not resolve HANDLER_NAME given in connect descriptor
- ORA-12525 TNS:listener has not received client's request in time allowed
- ORA-12526 TNS:listener: all appropriate instances are in restricted mode
- ORA-12527 TNS:listener: all instances are in restricted mode or blocking new connections
- ORA-12528 TNS:listener: all appropriate instances are blocking new connections