install : pip install pdfmerger --upgrade
Requirement already up-to-date: pdfmerger in c:\users\carlt\appdata\local\programs\python\python38\lib\site-packages (0.5.0)
Requirement already satisfied, skipping upgrade: PyPDF2 in c:\users\carlt\appdata\local\programs\python\python38\lib\site-packages (from pdfmerger) (1.26.0)

import : from PyPDF2 import PdfFileReader, PdfFileWriter

error : from PyPDF2 import PdfFileReader, PdfFileWriter