This is a resubmission of 4026405, which I would reopen if bugtraq allowed it.

A user suggests that 4026405 has not really been fixed:

  4026405 is not the same as 4024764. 4024764 is about appletviewer
  and jdb not working together. 4026405 is about remote debugging
  not working. Below is the text I submitted for 4026405. I think
  it's important to fix this because the jdb docs say remote debugging
  works but (to me, unless I'm doing something wrong) this bug says
  that remote debugging doesn't work at all. I've tried this under
  jdk 1.1 final and the crash I got was different but there was still
  a crash.

  If you don't think this is a bug can you tell me how to use jdb
  to attach to a remote Java program, and set a breakpoint? Please
  let me know the status. Thanks, - Mitch

It turns out that 4024764 and 4026405 are only tangentially related.

The problem with the example in 4026405 is that the user is running the
debuggee with java rather than java_g. Not surprisingly, setting a breakpoint
in the optimized interpreter causes it to crash. The breakpoint support code
really ought to check that it's running in a VM that supports debugging before
it sets a breakpoint.