Problems installing QGIS 2.14.14 and QGIS 2.18.6 (32-bit) on Windows Vista 32-bit AND QGIS 2.14 and QGIS 2.18.14 64-bit Windows 7 64-bit computer

Question

I used to have QGIS installed on my computer (functioning) but I decided recently to upgrade. However, attempts to install QGIS have failed. My computer is running Windows Vista (upgrading my operating system is not an option in my case) with 32-bit operating system.

During installation (which I have tried with both QGIS 2.18 and QGIS 2.14 several times now), the following error shows up: "Could not find C:/Program Files/QGIS 2.18/postinstall.log" but I can find a postinstall.txt file when I look manually When I try to open QGIS, I get the following error message: "This application failed to start because api.ms.wind.crt.runtime-l1-1-0.dll was not found. Re-installing the application may fix this problem."

If there is a known problem with the latest QGIS and older operating systems, what is the last version of QGIS that is known to work correctly with Windows Vista? [edit: I have successfully installed QGIS 2.10.1 on Windows Vista]

Additional issue: QGIS 2.18.14 (latest release in December 2017) nor QGIS 2.14 (long-term repository release) nor OSGeo4W does not install on my Windows 7 64-bit computer. No error messages were given during the Stand-alone installation but the same error message when I attempt to open QGIS pops up:

"This application failed to start because api.ms.wind.crt.runtime-l1-1-0.dll was not found. Re-installing the application may fix this problem."

Answer 1

I have overcome this issue after hours of trying on my Windows 7 x64. Here's how it worked for me:

1. I was getting the same error when launching QGIS2.18. It said that "This application failed to start because api.ms.wind.crt.runtime-l1-1-0.dll was not found. Re-installing the application may fix this problem." Tried re-installing, but didn't work.

2. First I had to install MS C++ Redistributable 2015 (Not sure if it's needed, but wouldn't hurt).

3. Then I needed to install Microsoft update KB2999226 (as suggested by many here). This Windows Update contains the missing api.ms.wind.crt.runtime-l1-1-0.dll file, so it's critical to have it on your PC. But here I encountered a major issue. Since I hadn't updated my Windows in a while, the .msu file would go on a never ending loop and get stuck. (If you don't face this, and are able to install KB2999226 successfully, you should be done at this point and QGIS should be working).

4. So I followed the Windows Service cleanup instructions here: https://www.howtogeek.com/247380/how-to-fix-windows-update-when-it-gets-stuck/. I a) turned off Windows Update, b) then from Services.msc, I stopped the windows update service, c) restarted in safe mode and cleared the contents in C:\Windows\Software Distribution folder, d) restarted in regular mode, and then e) installed KB3020369 (April 2015 servicing stack update for Windows 7), followed by KB3172605 (July 2016 update rollup for Windows 7 SP1) by following the instructions provided in the link. Finally, after restarting, and ensuring that my Windows Update service is still stopped, I installed the KB2999226 update. This time it got installed really fast (no more never-ending loop!), and then when I tried to launch: Voila! I had QGIS!!