# Can't set watchpoint

**URL:** <https://www.ruby-forum.com/t/cant-set-watchpoint/161465>\
**Category:** Ruby\
**Created:** [February 26, 2009, 7:07pm UTC](https://www.ruby-forum.com/t/cant-set-watchpoint/161465 "2009-02-26T19:07:00Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![wickie](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/w/ba9def/32.png) [@wickie](https://www.ruby-forum.com/u/wickie)\
**Post date:** [February 26, 2009, 7:07pm UTC](https://www.ruby-forum.com/t/cant-set-watchpoint/161465/1 "2009-02-26T19:07:00Z")

</div>

I’m running ruby 1.8.6 on Ubuntu Hardy.  
I have rdebug 0.10.3

I start rdebug on a script and try to issue a watch command such as

```
 watch n == 4

```

I immediately get the error  
NoMethodError Exception: undefined method `watch’ for  
#MP3File:0xb5cc7454

I then issue the command “help”. “watch” is not shown on the command  
list.

Can anyone offer some help.