Python 3.8: ImportError: DLL load failed while importing _psycopg: The specified module could not be found.

[juliavdkris]

TL; DR: update pip. See this comment

I get this error when trying to import psycopg2 in Python 3.8 on Windows 10. I already tried reinstalling (both psycopg2 and psycopg2-binary) and even reinstalling Postgres. Seems to work fine on Python 3.7.

>>> import psycopg2
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "D:\Documents\Programming\blokken\.venv\lib\site-packages\psycopg2\__init__.py", line 50, in <module>
    from psycopg2._psycopg import (                     # noqa
ImportError: DLL load failed while importing _psycopg: The specified module could not be found.

[dvarrazzo]

#990

[juliavdkris]

I think this is actually a different issue, this is a problem with importing the library, not with installation.

[heckad]

You just have installed Postgres in your os and because library installs successfully.

[hoysala-abhi]

Even Im facing same issue. Any luck with this ?

[juliavdkris]

Nope, looks like this won't get fixed until Appveyor adds Python 3.8 support. I had to just downgrade back to Python 3.7 for now. :/

[nevinhappy]

So the fix is waiting for new release to support 3.8 and walkaround is switching to 3.7 ？

[dvarrazzo]

FYI, if someone wants to fix the appveyor script and install Python 3.8 there for the build, be my guest.

[ShingenPizza]

So correct me if i'm wrong, but what i got from comments in other related issue threads here, the appveyor change/update is required to build and provide the binary package of psycopg2 for Python 3.8.

The problem is that the issue reported here, contrary to #1004, doesn't seem to be related to the lack of the binary package.

Because of the lack of a binary version, the package seems to be built by pip from sources locally, and i can also build it myself by downloading it manually.
In both cases it doesn't work when imported (at runtime) in Python 3.8 while it does in Python 3.7.
I clearly do pass the build prerequisites and runtime requirements.
The same error appears in Python 3.7 when i remove psql bin folder from PATH.
Is there a way to get the exact dll file that was not found from the ImportError? maybe that would shine some light here.
Should the appveyor issue also affect building the package from sources locally?

[jerickso]

To be honest, psycopg2's setup.py does a VERY poor job of building from source on end user's Windows. If someone is interested in improving it...

The windows environment has several challenges when building from source vs LINUX/UNIX, some of which:

• Need to have the correct Visual C compiler installed based upon Python version (how many of us have Visual C++ 14 installed?)
• Detect the location of the PostgreSQL build dependencies (includes/libs)
• Detect if we also need any OpenSSL dependencies based upon the PostgreSQL build and where those lib/include files are located
• If linking against DLL version of libpq, make sure all the appropriate DLLs (and correct versions) are accessible via the path

Also, the PostgreSQL binaries were probably built with a newer version of the Visual C compiler, causing the potential for multiple LIBC libraries being included into the process space when pscopyg2 is imported (This shouldn't be the case, but past experience is why we build ALL dependencies in Appveyor).

[hingston]

Appveyor has added Python 3.8 support. Could this please be a priority now?

[BrendanMartin]

I'm having this same problem.