I had a feeling boto3 or its dependencies were causing this issue, and seemed to be right.
I reinstalled Pythonista3 and imported flask without issues. Then I installed ptinstaller and stash and could still import flask (as expected). Then I installed boto3 (and deps) via pip/stash.
Restarted pythonista and tried to import flask. Then I received this error again!
Now I just installed flask via pip and this seems to work. I can now import flask and boto3.

Module pg8000 works indeed! Thanks guys!

Ah thank you for your reply.
Do you know if there is another way to connect to a postgres server?

Hi, I am trying to install psycopg2 but get the following error.
Any ideas?
Thanks
Stef
[~/Documents]$ pip install psycopg2
Querying PyPI ...
Downloading package ...
Opening: https://pypi.python.org/packages/7b/a8/dc2d50a6f37c157459cd18bab381c8e6134b9381b50fbe969997b2ae7dbc/psycopg2-2.6.2.tar.gz
Save as: /private/var/mobile/Containers/Data/Application/96C663CC-44E0-4415-B60D-C6C5E8888A33/tmp/psycopg2-2.6.2.tar.gz (376348 bytes)
376348 [100.00%]
Extracting archive file ...
Archive extracted.
Running setup file ...
ImportError('No module named lib2to3.refactor',)
Failed to run setup.py
Fall back to directory guessing ...
Error: Cannot locate packages. Manual installation required.

Thank you for your reply.
I see in stash that flask was not installed using pip... I could install it with pip but I'm afraid for weird side effects..

I suspect it must be something I installed which are causing this issues. I did install a few scripts using ptinstaller. I uninstalled them but still same error. I did install some packages using pip, like boto3. I'll check what others I installed using pip.

This is the complete list:
ywangd/pkg_resources (master) - Copied from setuptools so it can be downloaded separately without the whole lot
aws (0.2.5) - Utility to manage your Amazon Web Services and run Fabric against filtered set of EC2 instances.
boto (2.43.0) - Amazon Web Services Library
Fabric (1.9.2) - Fabric is a simple, Pythonic tool for remote execution and deployment.
PrettyTable (7) - A simple Python library for easily displaying tabular data in a visually appealing ASCII table format.
boto3 (1.4.1) - The AWS SDK for Python
botocore (1.4.66) - Low-level, data-driven core of boto 3.
jmespath (0.9.0) - JSON Matching Expressions
python-dateutil (2.5.3) - Extensions to the standard Python datetime module
docutils (0.12) - Docutils -- Python Documentation Utilities
s3transfer (0.1.9) - An Amazon S3 Transfer Manager
futures (3.0.5) - Backport of the concurrent.futures package from Python 3.2
pyte (0.4.10) - Simple VTXXX-compatible terminal emulator.
awscli (1.11.10) - Universal Command Line Environment for AWS.
colorama (0.3.7) - Cross-platform colored terminal text.
rsa (3.4.2) - Pure-Python RSA implementation
pyasn1 (0.1.9) - ASN.1 types and codecs
gitdb (0.6.4) - Git Object Database

Hi,
When I import flask I get the error below. I had this before and resolved it by reinstalling pythonista. After reinstalling I can import flask without issues (I am not really using it yet in my scripts but plan to do so soon), but later it fails again.
Any idea what could be wrong?
Thanks
Stef

import flask
Traceback (most recent call last):
File "<string>", line 1, in <module>
File "/var/containers/Bundle/Application/C30A01EF-6A6E-4EFE-8956-B463B1F36855/Pythonista3.app/Frameworks/PythonistaKit.framework/pylib/site-packages/flask/init.py", line 19, in <module>
from jinja2 import Markup, escape
File "/var/containers/Bundle/Application/C30A01EF-6A6E-4EFE-8956-B463B1F36855/Pythonista3.app/Frameworks/PythonistaKit.framework/pylib/site-packages/jinja2/init.py", line 33, in <module>
from jinja2.environment import Environment, Template
File "/var/containers/Bundle/Application/C30A01EF-6A6E-4EFE-8956-B463B1F36855/Pythonista3.app/Frameworks/PythonistaKit.framework/pylib/site-packages/jinja2/environment.py", line 13, in <module>
from jinja2 import nodes
File "/var/containers/Bundle/Application/C30A01EF-6A6E-4EFE-8956-B463B1F36855/Pythonista3.app/Frameworks/PythonistaKit.framework/pylib/site-packages/jinja2/nodes.py", line 18, in <module>
from jinja2.utils import Markup
File "/var/containers/Bundle/Application/C30A01EF-6A6E-4EFE-8956-B463B1F36855/Pythonista3.app/Frameworks/PythonistaKit.framework/pylib/site-packages/jinja2/utils.py", line 520, in <module>
from markupsafe import Markup, escape, soft_unicode
File "/var/containers/Bundle/Application/C30A01EF-6A6E-4EFE-8956-B463B1F36855/Pythonista3.app/Frameworks/PythonistaKit.framework/pylib/site-packages/markupsafe/init.py", line 228, in <module>
from markupsafe._speedups import escape, escape_silent, soft_unicode
File "/var/containers/Bundle/Application/C30A01EF-6A6E-4EFE-8956-B463B1F36855/Pythonista3.app/Frameworks/PythonistaKit.framework/pylib/site-packages/markupsafe/_speedups.py", line 7, in <module>
bootstrap()
File "/var/containers/Bundle/Application/C30A01EF-6A6E-4EFE-8956-B463B1F36855/Pythonista3.app/Frameworks/PythonistaKit.framework/pylib/site-packages/markupsafe/_speedups.py", line 6, in bootstrap
imp.load_dynamic(name,file)
AttributeError: 'module' object has no attribute 'load_dynamic'