At least we have more info on the error now. The 13 is EACCES. From MSVC docs:
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EACCES
Permission denied. The file's permission setting does not allow the specified access. This error signifies that an attempt was made to access a file (or, in some cases, a directory) in a way that is incompatible with the file's attributes.
For example, the error can occur when an attempt is made to read from a file that is not open, to open an existing read-only file for writing, or to open a directory instead of a file. Under MS-DOS operating system versions 3.0 and later, EACCES may also indicate a locking or sharing violation.
The error can also occur in an attempt to rename a file or directory or to remove an existing directory.
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This is most likely a sharing violation. Is ANYTHING reading progress.txt on your system, perhaps?