I installed QGIS 2.18 after i had uninstalled the version 2.16. It installed quite well but it is not starting at all. I went into the program directory and click on the exe file and got the error "The program can't start because qgis_app.dll is missing from your computer. Try reinstalling the program to fix this problem". I have installed severally and the same error keeps coming on. Any help?
I've had the same problem (missing dll files) with QGIS 2.14 LTR and I reinstalled several times. Opening QGIS with the bat file did not work.
My problem has been solved by uninstalling and searching for all "qgis" files (not the project files) on the C-drive and delete them (also temporary files).
After that and a fresh install of QGIS 2.14 LTR, it works!
I had this problem on an upgraded Win machine just now and the file to redirect to - for 2.14.1x at least is qgis-ltr.bat. All shortcuts / aliases should point to this.
Same problem. Go to C:\Program Files\QGIS 2.18\bin, copy qgis.bat.tmpl, and rename it to qgis.bat, open it. That's it!
I got this error with windows when I didn't install as administrator, reinstalling with elevated permissions solved it for me. To install as admin, right click on the installer exe and click 'run as administrator'.