ImportError: undefined symbol: PQencryptPasswordConn

[mathihg]

Hi,

I am all new to postgres and psycopg2 so I am sorry for my bad language and explaining.

I have an easy Python application running on a Revolution Pi but I get error when importing the psycopg2:

ImportError: undefined symbol: PQencryptPasswordConn

Here is my information

• OS: Raspbian Stretch (https://revolutionpi.de/shop/en/stretch)
• Psycopg version: 2.9.3
• Psycopg-binary version: 2.9.3
• Python version: 3.9.13
• PostgreSQL version: 9.6.24
• pip version: 22.1.2

I have tried reinstalling the packages using both pip and build from source, as many suggest from 1018 and 1093, but the error is still present.

What am I missing?

Thanks

[dvarrazzo]

Hello,

I suspect you have more than one libpq installed in the system: at build time a newer version is used (Postgres >= 10, which includes the above function), but at runtime an older version is found.

What have you got related to libpq in your system? You can check with:

find / -name \*libpq\*

What pg_config is found?

which pg_config
pg_config --version
pg_config --libdir

What libpq is being used at runtime? The libpq is dynamically linked to the C module, which is named in a pattern such as _psycopg.cpython-38-x86_64-linux-gnu.so, and should be found in a directory site-package/psycopg2 in your Python path.

# Find possible candidates
find . -name _psycopg\*.so

# for instance, on my system I get:
ldd ./build/lib.3.8/psycopg2/_psycopg.cpython-38-x86_64-linux-gnu.so
	linux-vdso.so.1 (0x00007ffc772e9000)
	libpq.so.5 => /lib/x86_64-linux-gnu/libpq.so.5 (0x00007fd94a8c5000)
	...

the last path is somewhere in your Python packages, it refers to a file

[mathihg]

Thank you for a quick respond!

The first command resulted in:

So the package is installed for python 3.9?

pg_config is located at /usr/bin/pg_config with version 9.6.24 and --libdir == /usr/lib/arm-linux-snueabihf

the command find - -name _psycopg\*.so results in
./.local/lib/python3.5/site-packages/psycopg2/_psycopg.cpython-35m-arm-linux-gnueabihf.so
in the python 3.5 path.

The application works fine when running on python 3.5, but how can I make it work with 3.9?

[dvarrazzo]

psycopg2cffi is a separate package: see here: https://pypi.org/project/psycopg2cffi/ If that's what you are trying to use you should hear from that project, not from this one.

The application works fine when running on python 3.5, but how can I make it work with 3.9?

I don't know which architecture the raspberry pi is, so I assume psycopg2-binary will not work. Try to remove every bit you find about psycopg, then pip install psycopg2 making sure that pip is related to Python 3.9.