pyinstaller --onefile generates 0KB exe

I have written a python script which converts all pdf present in a folder to docx (with the help of wincom package(pywin32)). The script works fine if I run the python script only in my windows10 x64 machine, but when I generate the exe through "pyinstaller --onefile pdf2docx.py" it generates an exe initially of some size(11MB) but once exe is completely generated it becomes 0 KB.

This is my code

import os, json, traceback, sys, shutil
import win32com.client
from datetime import datetime
from inspect import currentframe

# Global Variables
logfile = open("log.txt", 'a+')

# Returns Current line number (for Debugging purpose)
def get_linenumber():
    cf = currentframe()
    return "Line No: "+str(cf.f_back.f_lineno)

# Handels Error
def handel_error(line_no = None ,description = None, data = None):
    log(f"Ended with Error(logged in Error.txt): {datetime.now()}\n{'-'*80}\n")
    err = traceback.format_exc()
    err_path= f"Error.txt"
    with open(err_path,"a+") as f:
        f.write(f"\n{datetime.now()}\n{'-'*100}\nUnexpected error:\n{description} : {data} at {line_no}\n{err}\n{str(sys.exc_info())}\n")

#  Returns dictionary from json file
def read_config(config):
    with open(config, 'r') as f:
        return json.load(f)

# logs into log(txt format) file
def log(text, file = logfile):
    file.write(f"{text}\n")

# Converts All pdf files from PDF directory to Word file and place it in DOC directory (Directories are provided in the config.json file)
# If pop-up appears, check the checkbox Don't show again and press ok
def pdf2docx(pdf_dir,docx_dir):
    for fle in os.listdir(pdf_dir):
        pdf = os.path.join(pdf_dir, fle)
        name,ext = os.path.splitext(fle)
        if ext == '.pdf':
            try:
                log(f"Processing : {fle}")
                wb = word.Documents.Open(pdf)
                out_file = os.path.abspath(f"{docx_dir}\\{name}.docx")
                print("Processing: ",fle)
                wb.SaveAs2(out_file, FileFormat=16) # file format for docx
                log("success...")
                wb.Close()
            except:
                handel_error()
        else:
            log(f"Not a pdf file: {fle}")

if __name__ == "__main__":
    try:
        # Reading the configuration file
        base_dir = os.path.dirname(os.path.abspath(__file__))
        config = read_config(f"{base_dir}\\config.json")
        pdf_dir = config['pdfs']
        docx_dir = config['docx']
        
        log(f"Started: {datetime.now()}\n")

        # Converting pdf to word
        word = win32com.client.Dispatch("Word.Application")
        word.visible = 0
        
        pdf2docx(pdf_dir,docx_dir)

        word.Quit()

        log(f"\nEnded: {datetime.now()}\n{'-'*80}\n")
    except:
        handel_error()

I'm more interested in knowing the root cause than the solution. Please help me and Thanks in advance. :)