[GIS] QGIS 2.18 ImportError: DLL load failed: The specified module could not be found

pyqgispyqt4qgis-2.18

I try to run the QSwat script and it begins with that:

from PyQt4.QtCore import * # @UnusedWildImport
from PyQt4.QtGui import * # @UnusedWildImport
from qgis.core import * # @UnusedWildImport
from qgis.gui import * # @UnusedWildImport

However I get this error:

Traceback (most recent call last):
  File "C:/Program Files/QGIS 2.18/apps/qgis/python/plugins/HidroTurk/HT_HJK/delineation.py", line 25, in <module>
    from qgis.core import * # @UnusedWildImport
  File "C:\Program Files\QGIS 2.18\apps\qgis\python\qgis\__init__.py", line 26, in <module>
    from qgis.PyQt import QtCore
  File "C:\Program Files\QGIS 2.18\apps\qgis\python\qgis\PyQt\QtCore.py", line 28, in <module>
    sip.setapi(api, 2)
ValueError: API 'QDate' has already been set to version 1

I read that if I import qgis.core and qgis.gui later, it fixes the problem so I wrote like that:

from qgis.core import * # @UnusedWildImport
from qgis.gui import * # @UnusedWildImport
from PyQt4.QtCore import * # @UnusedWildImport
from PyQt4.QtGui import * # @UnusedWildImport

I got this error:

Traceback (most recent call last):
  File "C:/Program Files/QGIS 2.18/apps/qgis/python/plugins/HidroTurk/HT_HJK/delineation.py", line 23, in <module>
    from qgis.core import * # @UnusedWildImport
  File "C:\Program Files\QGIS 2.18\apps\qgis\python\qgis\__init__.py", line 27, in <module>
    from qgis.core import QgsFeature, QgsGeometry
  File "C:\Program Files\QGIS 2.18\apps\qgis\python\qgis\core\__init__.py", line 30, in <module>
    from qgis._core import *
ImportError: DLL load failed: The specified module could not be found

I am sure that the problem source is PATH, PYTHONPATH and PYTHONHOME. Because I got this error in QGIS 3 and I solved it by adding paths that can be reached by writing python console print (sys.path) to the system variables of PATH and PYTHONPATH.

However I can not fix it with the same way. I have been handling with it for 5 days and I will go crazy!

Note: I can import them in QGIS 2.18 python console.

Best Answer

I'm using a batchfile to set the environment for python and qgis, like this:

SET QGIS_PREFIX_PATH=%OSGEO4W_ROOT:\=/%/apps/qgis
SET PYTHONPATH=%OSGEO4W_ROOT%\apps\qgis\python
SET PYTHONHOME=%OSGEO4W_ROOT%\apps\Python27
SET PATH=%PATH%;%OSGEO4W_ROOT%\apps\Python27\Scripts;%OSGEO4W_ROOT%\apps\qgis\bin

I put this batch file into the directory %OSGEO4W_ROOT%\etc\ini which is autmatically called by the OSGeo4W-Shell, or you can start mostly any Python-IDE by batch file and call that ini-batch file (here for pyscripter):

set PYSC_DIR=%~dp0

for %%F in ("%OSGEO4W_ROOT%\etc\ini\*.bat") do call "%%F"

SET PYTHONPATH=%PYTHONPATH%;%PYSC_DIR%;%PYSC_DIR%\lib;
SET PATH=%PYSC_DIR%;%PATH%

start "PyScripter" %PYSC_DIR%\PyScripter.exe --python27 --pythondllpath=%OSGEO4W_ROOT%\bin
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