An NSIS error appears every time I try to install.

How do I fix the Nsis error? any help is appreciated.

I have Win 8.1 (64-bit) and tried to download and install Unity 5.1.1f with Chrome. Installation end up with NSIS error. I switched virus protection (Avast) off and used Chrome Download manager. Same NSIS error. I turned virus protection on again. Then I tried to use Internet Explorer with same result. I also tried this command prompt trick with same results. But then I tried with Internet Explorer and switched off Avast virus protection and that worked!

Google turns this up:

The installer has failed a self-check. This means that for some actions, the installer file has been altered from its original form. If the install were to continue, the software install would not be complete and will be broken. To prevent further problems, the installer refused to continue.

Check out this page for possible remedies:

  1. Open cmd
  2. Drag your unity installer into the
  3. press space and type /NCRC
  4. Press Enter

this works for me everytime :slight_smile: