PermissionError: [WinError 32] when updating existing fits file

Question

I'm working on win11 with python 3.9.7 and I'm trying to open a fits datacube that has different layers and append a new one and then save it, but when I do that, I get the following error: "PermissionError: [WinError 32] The process cannot access the file because it is being used by another process"

This is an example of what I'm trying to do:

from astropy.io import fits
Datacube=fits.open(path2tile,memmap=False,mode='update')
Datacube.append(fits.ImageHDU(data=data,name='new layer'))
print(Datacube.info())
Datacube.writeto(path2tile,overwrite=True)

where path2tile is some path to the datacube I want to open and data is the new data I want to append to the existing datacube. I also tested different mode options but nothing works so far.

This is the output of the print statement:

No.    Name      Ver    Type      Cards   Dimensions   Format
  0  PRIMARY       1 PrimaryHDU       4   ()      
  1  SCI           1 ImageHDU         8   (31, 31)   float64   
  2  ERR           1 ImageHDU         8   (31, 31)   float64   
  3  DQ            1 ImageHDU         8   (31, 31)   float64   
  4  CRCELANSCI    1 ImageHDU         8   (31, 31)   float32   
  5  NEW LAYER     1 ImageHDU         8   (31, 31)   float32  

So the new data is actually appended to the datacube, but for some reason, it can not be saved. The error is happening at the Datacube.writeto(path2tile,overwrite=True) line when it try to save the file. Anyone has any idea why this is happening and how can I fix it/bypass it?

Answer 1

To anyone looking for an answer to this problem, this is the solution I found:

 from astropy.io import fits
 Datacube=fits.open(path2tile,memmap=False,mode='update')
 Datacube.append(fits.ImageHDU(data=data,name='new layer'))
 print(Datacube.info())
 Datacube.flush()

With the 'update' mode I just swapped the witeto() with flush() and it's working now. No more "PermissionError: [WinError 32] The process cannot access the file because it is being used by another process"