I downloaded the Visual Composer 4.7.4 and uploaded it to my site via ftp. I can see the plugin in my dashboard plugin area. When I try to activate the plugin, I get this error:
Plugin could not be activated because it triggered a fatal error.
Fatal error: Cannot redeclare wpb_getImageBySize() (previously
declared in
/home/riiott/public_html/wp-content/themes/effectivenews/composer/js_composer/composer/lib/helpers.php:27)
in /home/riiott/public_html/wp-content/plugins/js_composer/include/helpers/helpers.php on line 110
it seems like your theme “Effective News” is shipping with a built-in version of Visual Composer, which should not be the case anymore, as plugins like VC should not be run from inside the theme folder anymore, but installed as standalone plugin.
Unless your theme allows you to disable its built-in version of VC, you will not be able to run the standalone version, as it will always cause the described error, because you are basically attempting to run two versions of VC at the same time.
You can attempt to copy your standalone VC version into the specified theme folder, replacing the theme version, but as your theme most likely customized VC, that might not work either.
Unfortunately the theme has been removed from ThemeForest and the author’s website has been taken down as well. It’s a good theme, I’d like to be able to keep it.