Python exe complains about ModuleNotFoundError about inbuilt module json

Question

I have built an exe using pyinstaller. Before building exe, I made sure my main script of the project works using python command. I am using Virtual environment. So I made sure it was activated and it has all requirements of the project. (Json is anyways inbuilt) My exe gets built successfully but then When I execute exe, I see the following error.

Traceback (most recent call last):
  File "Main.py", line 15, in <module>
  File "C:\TestAutomation\Frontend\src\json_database.py", line 2, in <module>
    import json
ModuleNotFoundError: No module named 'json'

I dont understand on how to proceed