Type Reason ArgumentNullException obj is null. System.Threading.SynchronizationLockException The calling thread does not own the lock for the specified object.
The thread that currently owns the lock on the specified object invokes this method to signal all threads waiting to acquire the lock on the object. After the signal is sent, the waiting threads are moved to the ready queue. When the thread that invoked PulseAll releases the lock, the next thread in the ready queue acquires the lock.
Note that a synchronized object holds several references, including a reference to the thread that currently holds the lock, a reference to the ready queue, which contains the threads that are ready to obtain the lock, and a reference to the waiting queue, which contains the threads that are waiting for notification of a change in the object's state.
To signal a single thread, use the Pulse method.