ValueError: Inferred frequency None from passed values does not conform to passed frequency MS

[KAMALESAKUMARV]

Traceback:
File "C:\SALES PREDICT\VirEnv\env\lib\site-packages\streamlit\runtime\scriptrunner\script_runner.py", line 565, in _run_script
exec(code, module.dict)
File "C:\SALES PREDICT\VirEnv\RetailSensei\app.py", line 51, in
datasets = Datasets()
File "C:\SALES PREDICT\VirEnv\RetailSensei\read_datasets.py", line 21, in init
self.test.index.freq = 'MS'
File "C:\SALES PREDICT\VirEnv\env\lib\site-packages\pandas\core\indexes\extension.py", line 81, in fset
setattr(self._data, name, value)
File "C:\SALES PREDICT\VirEnv\env\lib\site-packages\pandas\core\arrays\datetimelike.py", line 937, in freq
self._validate_frequency(self, value)
File "C:\SALES PREDICT\VirEnv\env\lib\site-packages\pandas\core\arrays\datetimelike.py", line 1019, in _validate_frequency
raise ValueError(