What will be the result of writing to a closed channel? Deadlock, panic, or a write operation error?

In Go, writing to a closed channel causes a panic.

If you try to send a value to a channel that is already closed, the runtime triggers a panic with the message "send on closed channel".

Example:

ch := make(chan int)
close(ch)
ch <- 1 // panic: send on closed channel

Therefore, a write operation to a closed channel does not return an error or block — it immediately causes a panic. To avoid this, you need to ensure that writing only occurs to an open channel, for example, by using additional flags or synchronization.