Fails to copy python3.dll to Virtualenv under Windows

[jdmansour]

When creating a Virtualenv under Windows (using Python 3.6), it seems to work fine at first, but some modules (notably PyQt5) complain with ImportError: DLL load failed: The specified module could not be found.. The cause is that it fails to find python3.dll (not python3.6.dll). Manually copying it to the Scripts directory fixes the problem.

Another option would be to add the original Python directory to the PATH, but I think that might cause problems. Better to keep the Virtualenv separate from the main installation, at the expense of copying one more file.

I wonder how this is handled under Linux, I never had that problem there?

Here somebody mentions the problem in a different isue: #796 (comment)
I think this issue is related, but for Linux: #1015

[gst]

effectively this really looks like 1015 but on Windows.

I wonder how this is handled under Linux, I never had that problem there?

simply Linux system pythons (python coming with the Linux distributions) aren't compiled with that option (relative path to the shared library).
you have to compile one by hand and provide the option.

[gst]

@jdmansour fyi: python3 has its embedded venv module.. which is normally recommended over virtualenv

[jdmansour]

@gst Interesting, I always thought that the builtin venv was identical to virtualenv. I just tried it out, and python -m venv myvenv does copy python3.dll. So I guess it would be good if virtualenv did the same for consistency (if you are still maintaining it, given there is venv in Python 3)?

One added complication is that I used virtualenvwrapper (or virtualenvwrapper-win) which seems to insist on using virtualenv the package.

[gst]

I m a user like you here ;) venv vs virtualenv: they are not the same yes.
If you are using python3 just use venv and all should be good I guess (had not the chance to use it/python3 recently).

[brupelo]

@dstufft Hi Donald, sorry to ping you but I've seen in the commit history you're a major contributor of virtualenv. Any possible solution about trivial issue?

Running virtualenv 15.1.0 on a windows platform will show this issue after installing pyqt5. Copying
manually the missing python3.dll to the Script folder will solve it.

So, wouldn't something like copying python3*.dll on the virtualenv Scripts folder if platform==windows solve it?