End of Life Ruby 3.0 has reached end of life and gets no more fixes. Switch to Ruby 4.0 →

class method

Thread.report_on_exception=

Thread.report_on_exception= boolean → true or false

static VALUE
rb_thread_s_report_exc_set(VALUE self, VALUE val)
{
    GET_THREAD()->vm->thread_report_on_exception = RTEST(val);
    return val;
}

Returns the new state. When set to true, all threads created afterwards will inherit the condition and report a message on $stderr if an exception kills a thread:

Example

Thread.report_on_exception = true
t1 = Thread.new do
  puts  "In new thread"
  raise "Exception from thread"
end
sleep(1)
puts "In the main thread"

This will produce:

In new thread
#<Thread:...prog.rb:2> terminated with exception (report_on_exception is true):
Traceback (most recent call last):
prog.rb:4:in `block in <main>': Exception from thread (RuntimeError)
In the main thread