Keil Arm Compiler Version 5 Download Portable -

You installed a clean copy of MDK 5.38 or 5.39, which never included v5.

Set the installation path to a subfolder within your Keil installation directory, such as C:\Keil_v5\ARM\ARM_Compiler_5.06u7 . keil arm compiler version 5 download

If you want, I can expand this into:

Older projects often use syntax or pragmas specific to armcc that aren't compatible with armclang . You installed a clean copy of MDK 5