I was following this guide https://realpython.com/blog/python/setting-up-a-simple-ocr-server/ and got to the part where I run cli.py python flask_server/cli.py
Python import
errors usually boils down to one of those three cases (whether is is modules you developed; or modules distributed as packages):
You did no install the required package. Googling pytesseract
tells me its an OCR that is distributed and installable using Python package manager tool pip
by running pip install pytesseract
in your favorite shell.
You did install the package, but is is not in your python path.
(Less often) You did install the package, and it is in your python path, but you used a name already in user by Python, and the two are conflicting.
In your case, I strongly think this is the first one. Case 2. and 3. can be assessed by calling python -v your_script.py
as described in this answer.