Error oracle- ORA-00021: session attached to some other process; cannot switch session

ORA-00021: session attached to some other process; cannot switch session

Cause:     The user session is currently used by others.

Action:     Do not switch to a session attached to some other process.

Error oracle- ORA-00020: maximum number of processes (string) exceeded

ORA-00020: maximum number of processes (string) exceeded

Cause:     All process state objects are in use.

Action:     Increase the value of the PROCESSES initialization parameter.

Error oracle- ORA-00019: maximum number of session licenses exceeded

ORA-00019: maximum number of session licenses exceeded

Cause:     All licenses are in use.

Action: Increase the value of the LICENSE MAX SESSIONS initialization parameter.