Not starting game with 'OSError: [WinError 6] The handle is invalid' error? Launches fine in MultiMC

[mattp12]

The message that shows when it fails to start

---

SYSTEM INFORMATION

Platform: Windows-10-10.0.16299
OpenMineMods Version: 2.1.5
Locale: ('en_US', 'cp1252')
Data Location: C:/Users/{USER}/AppData/Local\openminemods
Cache Location: C:/Users/{USER}/AppData/Local/cache\openminemods
Time: 1509664276

STACKTRACE

OSError: [WinError 6] The handle is invalid

File "subprocess.py", line 665, in init

File "subprocess.py", line 885, in _get_handles

---

SETTINGS

[Settings]
analytics = True
autoupdate = True
askfile = True
currentversion = 2.1.5
uuid = 0c537b5a-2c39-4832-a5fa-aeaa84146568
livesearch = True
metainterval = 24
clientinterval = 48

[MultiMC]
location = C:/Users/{USER}/Desktop/mmc-stable-win32/MultiMC

[Timestamps]
lastclient = 1509663392
lastmeta = 1509663390

Happens with any pack. I tried installing one through OMM and it still doesn't work. The directroy for MultiMC is correct.
I originally thought it would'nt start because I had MultiMC open as well as OMM, but that wasn't the case.
Win10, latest updates.