If you use a python venv (as I think):

The problem is a session that is bad terminated, ODOO restart the service but not use VENV context so python3 doesn't find correct dependencies

See the correct mode to launch if venv is used:

https://github.com/odoo/odoo/issues/33479#issuecomment-1207347677

Same error here. the server can launch successful, but failed after couple of hours, and show following erorr:

Mar 14 22:51:28 iZbp1feheb80mwpd2778a7Z odoo-15[3189]: Traceback (most recent call last):
Mar 14 22:51:28 iZbp1feheb80mwpd2778a7Z odoo-15[3189]: File "/home/odoo/odoo-15/odoo-bin", line 5, in
Mar 14 22:51:28 iZbp1feheb80mwpd2778a7Z odoo-15[3189]: import odoo
Mar 14 22:51:28 iZbp1feheb80mwpd2778a7Z odoo-15[3189]: File "/home/odoo/odoo-15/odoo/__init__.py", line 75, in
Mar 14 22:51:28 iZbp1feheb80mwpd2778a7Z odoo-15[3189]: import PyPDF2
Mar 14 22:51:28 iZbp1feheb80mwpd2778a7Z odoo-15[3189]: ModuleNotFoundError: No module named 'PyPDF2'
Mar 14 22:51:28 iZbp1feheb80mwpd2778a7Z systemd[1]: odoo-15.service: Main process exited, code=exited, status=1/FAILURE
Mar 14 22:51:28 iZbp1feheb80mwpd2778a7Z systemd[1]: odoo-15.service: Failed with result 'exit-code'.

How should I do?

if you are using pycharm, that may cause from Python Interpreter Environment .

FILE |Settings| Project xxx |Python Interpreter installation path or  choose Setting => Add : Python System interpreter that will include almost module necessary to run Odoo

Good luck

Go to environment step and run this command apt-get install python3-pypdf2 
Remember console will tell you to other dependency jinja2 and then just add the name of the package, for instance, apt-get install python3-psutil

tried, I still get the same error of "ModuleNotFoundError: No module named 'PyPDF2'".

Another workaround is to do the following:

apt-get install python-pypdf2

dpkg --ignore-depends=python-pypdf -i odoo_*

Again the Same Issue:

odoo@ebslubuntu2:/opt/11$ ./odoo-bin --xmlrpc-port=9000

Traceback (most recent call last):

File "./odoo-bin", line 5, in <module>

import odoo

File "/opt/11/odoo/__init__.py", line 84, in <module>

from . import modules

File "/opt/11/odoo/modules/__init__.py", line 8, in <module>

from . import db, graph, loading, migration, module, registry

File "/opt/11/odoo/modules/graph.py", line 10, in <module>

import odoo.tools as tools

File "/opt/11/odoo/tools/__init__.py", line 7, in <module>

from . import pdf

File "/opt/11/odoo/tools/pdf.py", line 4, in <module>

from PyPDF2 import PdfFileWriter, PdfFileReader

ImportError: No module named 'PyPDF2'

Hi,

Try This. Your one not working with python 3.

sudo apt install python3-pip

pip3 install -U pip

sudo pip3 install pypdf2