NSIS stands for 'Nullsoft Scriptable Install System'. It is an open-source, script-impelled system meant for installation. NSIS creates installers for software. In short, NSIS is not a software that one should install, it is merely the software that facilitates installion of other software on your system. NSIS should be reliable as well as stable since it's instrumental in inscribing the software the users require on their system. Its small size and fast speed makes its user-friendly. This installer can also be compiled on systems having operating systems other than Windows too. Besides this, the major advantage of NSIS installer is its compatibility with many important Windows versions which makes it possible to create just one installer. As we know, NSIS installers are widely used for software installation. However, if due to some reason the downloaded file has been manipulated, NSIS error will be thrown. If the installation process is continued despite the error, the software will not be installed properly. While trying to install software which use NSIS as the installer, the following NSIS error messages may possibly be displayed depending on the version of NSIS. ◇ Computer could be virus-infected. ◇ Incomplete download of the program from the Internet. ◇ Original file has been manipulated post-download. ◇ Due to hardware error. ◇ Wrongly done system configuration settings. ◇ Firewalls installed on the system. ▷ Error Due to Virus-affected Computer: A possible reason for NSIS error can be the entry of virus on your system. If your system has an antivirus program installed, check if its virus definitions are up-to-date. If not, update the antivirus. Try running the installer. If this doesn't work, disable the existing antivirus software. Try installing the desired program again. ▷ Error Due to Interrupted Download: If the software download did not complete successfully due to reasons such as poor Internet connectivity, or power outage, clear the browsers cache memory before re-installing the program. ▷ Error Due to Altered File: The file was manipulated in some way post its download on the system. This is one of the most important reasons for the NSIS error. This can be eliminated by re-downloading the installer. ▷ Error Due to Hardware Issues: If the program to be installed is in a removable drive, CD, or a DVD, and if NSIS error pops up, check if the other files from the same disk are opening. If not, then it means the disk is damaged. Eject and wipe this disk with a clean cloth by using a cleansing liquid. Re-insert the disk into the system and run the installer program. ▷ Error Due to Improper System Settings: Certain Windows drivers may need updation. Ensure that all the drivers are updated before you try to re-run the installer. ▷ Error due to Installed Firewalls: If a firewall is installed on your system, it may restrict the installation of a new program. To avoid this, disable the Firewall settings until the program is installed. Post program installation, the Firewall must be enabled. ▷ Error due to Download Manager Programs: If the system has any task accelerators to quicken the download process, it may be throwing the NSIS error. Uninstall any such programs. Run the installer again. ▷ Error due to Server Issues: The server may be experiencing some technical glitches, or the file may be corrupt at the server end. This is a rare scenario which cannot be avoided. Reinstall the program to check if the file is genuine. If not, download it again from some trusted website. ◾ If none of the techniques work in your favor, download the installer on any other computer and copy the installer file onto this computer. ◾ If you have uninstalled the antivirus program for tackling the NSIS error, make sure you re-install the antivirus program, as your system will be at risk from viruses if not done so. ◾ If the downloaded file seems to be corrupt, try downloading it from some other website. If on trying the above mentioned methods you were still not able to resolve the NSIS error, try getting help from the publisher of the application you have been trying to install.