Serial monitor won't open after "Error opening serial port 'COM12'. (Port not found)" under latest hourly build

[per1234]

Under Windows 7 64 bit using Arduino IDE hourly build 2015/06/01 09:34:
Once I get the Error opening serial port 'COM12'. (Port not found) error the serial monitor won't open any port until the IDE is restarted. This happens with any com port number. I don't have this problem under 1.6.4. It is a bit difficult to get the error message. I can get it sometimes by:

• Plug in the board to USB
• Select a different port from the one the board is on
• Select the port the board is on
• Unplug the board from USB
• Try to open the serial monitor. Console shows Error opening serial port 'COM12'. (Port not found). If that error doesn't show then restart the IDE and repeat the process.
• Plug the board back in to USB
• Verify the port shows in the ports menu
• Open serial monitor. Nothing happens. The same will happen for boards on a different port.

It may take a few tries to get the error message. I do not have this problem after the more common Board at COM12 is not available error.

[ffissore]

Related to #3255. Fix under way

[ffissore]

Should be fixed in latest hourly build http://www.arduino.cc/en/Main/Software#hourly Can you give it a try?

[per1234]

Hourly Build 2015/06/01 12:19, still same problem.
This has happened for me with FTDI connected to Pro Mini, Mega2560, and Pro Micro so it may be different from #3255 which sounds like it is related to Due/Leonardo.

[per1234]

I can still upload sketches after I get the error and serial monitor won't open so the serial port is still working, just not the serial monitor.

[smeezekitty]

I'm still experiencing this bug in 1.8.2