Why do I get NSIS Error?

A NSIS Error message box means the installer you're trying to run is corrupted. It means the installer data was somehow modified and is no longer valid. The error states:

The installer you are trying to use is corrupted or incomplete.
This could be the result of a damaged disk, a failed download or a virus.

You may want to contact the author of this installer to obtain a new copy.

It may be possible to skip this check using the /NCRC command line switch
(NOT RECOMMENDED).

Solutions

Follow these steps for each case to get rid of the error.

Error with Single Installer

1. Disable any download accelerators and download the installer again.
2. Update any active anti-virus and download the installer again.
3. Disable any active anti-virus and download the installer again.
4. Download the installer from another source. It might be corrupted on the server, or the connection to the server is unreliable.
5. Download the installer using another computer and copy it to the original computer using a reliable media.

Error with Multiple Installers

1. Disable any download accelerators and download the installer again.
2. Scan for, and remove malware
3. Scan for, and remove viruses
4. Scan the hard drive using scandisk, chkdsk, or any other hard drive repair tool
5. Download the installer using another network connection and copy it to the original computer using a reliable media.

Random or Start-up Errors

1. Scan for, and remove malware