Sometime in the last week our Windows pip-pre job in MNE-Python started failing with:

mne\io\base.py:2376: in _allocate_data
    data = np.memmap(str(preload), mode="w+", dtype=dtype, shape=shape)
C:\hostedtoolcache\windows\Python\3.11.7\x64\Lib\site-packages\numpy\_core\memmap.py:233: in __new__
    f_ctx = open(
E   OSError: [Errno 22] Invalid argument: 'memmap.dat'

I restarted the job and got the same error. I find this a bit baffling and am not 100% sure this is a NumPy issue. I see #25409 touched memmap.py in the right time frame but I am not sure how __array_wrap__ could be a culprit here. Notably there is no failure on Linux pip-pre so somehow this is Windows-specific. EDIT: Also no failure on other Windows jobs so it seems likely to be NumPy 2.0.0.dev0-specific, too.

I will try to replicate locally on my Windows boot tomorrow but wanted to throw this out there in case anyone had ideas for immediate culprits. I thought maybe pytest could be an issue but their last stable 7.4.4 came out weeks ago and we've had green builds since then.