Updating existing Excel file with Pandas and Openpyxl throws an AttributeError: property 'book' of 'OpenpyxlWriter' object has no setter

I have been trying to update data in an existing Excel--the process as follows:

1)read the data from Excel

2)combine it with a new data using pandas

3)save the combined dataframe into the original file

It keeps return the following error, which I think it is coming from writing(updating) the same file while reading it:

AttributeError                            Traceback (most recent call last)
Cell In[14], line 19
     18 with pd.ExcelWriter(file_path, engine='openpyxl') as writer:
---> 19     writer.book = book
     20     writer.sheets = {ws.title: ws for ws in book.worksheets}

AttributeError: property 'book' of 'OpenpyxlWriter' object has no setter

My code is here--running it also erases the data of the original file and make the file unusable:

# Load the Excel file
file_path = 'original.xlsx'
update = 'update.xlsx'

# Open the file in read-only mode to prevent any locks
with open(file_path, "rb") as file:
    book = load_workbook(file)

# Combine original with update file
for sheet_name in ['sheet1', ...]:
    df1 = pd.read_excel(file_path, sheet_name = sheet_name)
    df2 = pd.read_excel(update, sheet_name = sheet_name)
    df2 = df2.iloc[::-1]
    df1 = pd.concat([df1, df2], ignore_index = True)
    df1 = df1.drop_duplicates(subset = 'column1', keep = 'last')

    # Write combined data to the sheet
    with pd.ExcelWriter(file_path, engine='openpyxl') as writer:
        writer.book = book
        writer.sheets = {ws.title: ws for ws in book.worksheets}
        
        # Set the sheet as the active sheet
        book.active = book.sheetnames.index(sheet_name)
        
        df1.to_excel(writer, sheet_name = sheet_name, index = False, startrow = 1)

    print(f"Successfully updated '{sheet_name}' sheet in '{file_path}'.")

This is because book is read-only property.

Since you're only updating a file, you may try append mode with flags a and if_sheet_exists, provided by Pandas: docs

Result will look similar to that:

# Combine original with update file
for sheet_name in ['sheet1', 'sheet2']:
    df1 = pd.read_excel(file_path, sheet_name=sheet_name)
    df2 = pd.read_excel(update, sheet_name=sheet_name)
    df2 = df2.iloc[::-1]
    df1 = pd.concat([df1, df2], ignore_index=True)
    df1 = df1.drop_duplicates(subset='column1', keep='last')

    # Write combined data to the sheet
    with pd.ExcelWriter(file_path, mode='a', if_sheet_exists='replace', engine='openpyxl') as writer:
        df1.to_excel(writer, sheet_name=sheet_name, index=False, startrow=0)

    print(f"Successfully updated '{sheet_name}' sheet in '{file_path}'.")