Sample code below

import re

regex = r'DELETE\s*(?P<table_alias>[a-zA-z_0-9]*)\s*FROM\s*(?P<table_name>[a-zA-z_0-9]+)\s*([a-zA-Z0-9_]*)\s*(?P<where_statement>WHERE){0,1}(\s.)*?'

test_str = 'DELETE FROM my_table1 t_ WHERE id in (1,2,3)'

matches = re.finditer(regex, test_str, re.MULTILINE)

print([m.groupdict() for m in matches])

Below is the expected output.

[{'table_alias': '', 'table_name': 'my_table1', 'where_statement': 'WHERE'}]

But in Win Server 2012 R2, the output is
[{'table_alias': '', 'table_name': 'mytable1', 'where_statement': None}]

Using 3.7 in Win Server 2012 R2 also the output is not as expected. But in Win 10 and other linux variants, expected output is obtained.

In my test in win2012r2, it works well. Add a screenshot.

The regular expression engine is not platform depended.

Please check that you run the same code.

I was able to recreate the 'bad' output on Linux using 'bad' input.

The issue is caused when you misspell WHERE, regex is looking for the exact word "WHERE", any lowercase (where), multicase (WHeRe), or misspelling (WERE) is going to cause it to return None because regex didn't find a matching substring.

I also on a whim tested out a bunch of encodings before realizing it didn't run on bytes objects anyways, so really the only way to get this output is to misspell the input. I think this problem should probably be closed as it's not a bug with the python core.

For case-insensitive matching you can use the re.IGNORECASE flag.