QGIS: custom build, python error

Question

I have built qgis source on windows 7. Libs have been downloaded from osgeow4 site. I even installed postgress as a standalone.

I am getting this error when the app launches..

File "C:/development/qgis2.9.0/./python/plugins\processing\algs\qgis\postgis_utils.py", line 28, in import psycopg2
File "C:/development/qgis2.9.0/./python\qgis\utils.py", line 483, in _import mod = _builtin_import(name, globals, locals, fromlist, level)
File "C:\development\OSGeo4W\apps\Python27\Lib\site-packages\psycopg2__init__.py", line 71, in from psycopg2._psycopg import BINARY, NUMBER, STRING, DATETIME, ROWID
File "C:/development/qgis2.9.0/./python\qgis\utils.py", line 483, in _import mod = _builtin_import(name, globals, locals, fromlist, level) ImportError: DLL load failed: The specified module could not be found.

I have check all my python paths etc, but am not sure what about the psycopg2 plugin is missing.

Any direction would be great.

• ustroetz: psycopg2 lets you connect to the Postgres database. Open a python terminal and try to import psycopg2. If it throws an error you need to install it. You can download a windows install here: stickpeople.com/projects/python/win-psycopg
• Omnia9: @ustroetz I don't get an error. I used the libs from OSGeo to get the base. I even installed postgres just now. It has not changed the error.

Answer 1

I don't have any guesses why the osgeo4w installer would leave you in this state. I would have guessed that it would install all the necessary DLLs.

But my experience with "The specified module cannot be found" is that it's nearly always one of two things:

1. A problem with the PATH environment variable so that Python (or whatever) can't find your PostgreSQL client libraries (i.e. the stuff that lives in C:\Program Files\PostgreSQL9円.3\bin) or
2. An architecture mismatch between Python and the PostgreSQL libraries (e.g. your Python is 32 bit and your PostgreSQL is 64 bit).

If you have the know-how, maybe you could check those things to see if there's a problem.

• Omnia9: Thank you for this. I'm cleaning up my installs and will try this all again.