How to prevent Firefox’ plugin hang detector from triggering during Flex development

Firefox’ plugin hang detector is a feature that aims to reduce browser crashing caused by plugins like Flash or Silverlight hanging for prolonged periods of time. Firefox will cut a plugin process off after a predefined timeout, set to 15 seconds by default. While I loudly applaud this stability feature, it is an annoying one to deal with if you’re a Flash developer using a debugger. Setting breakpoints for longer than 15 seconds will trigger the hang detector and break off your debugging session. Very annoying indeed.

Fortunately, there is a way to disable this feature (or set the timout to something more usable).
Here’s how.

Step 1: about:config

Open up a new tab and type about:config to bring up the advanced configuration page. Click past the warning ;-).

Step 2: Set timeout to -1 to disable

Use the filter field to search for dom.ipc.plugins.timeoutSecs and set its value to -1 to disable the detector entirely. Of course, you’re free to set it to any higher value, just remember that the timeout is expressed in seconds and you’re good to go.


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