How to fix
“Invalid Signature” Error
on Windows

I have recently tried to install Avast and got “Avast Antivirus installer is unable to continue because the installer is corrupted or is forbidden to run on this machine.” How do I know which version to install? Or is it a virus?

Invalid Signature error might be the primary indicator suggesting that you attempt to install an “unofficial” application, i.e. corrupted one. Code signing refers to the phenomenon that each software is signed with a specific “signature” and has a certificate. They indicate that the software can be trusted. Current versions of Windows have a better detection technique.

Alternatively, the error notification might not always reflect the real situation. Users may spot the message which only appears when attempting to install one application or be deprived of installing any application. In addition, in rare cases, the fault may lie in hardware – faulty memory cards. Let us discuss the key solution options of “Invalid Signature” error.

Option 1. The Software is Corrupted

If you have attempted to install the application from secondary source, there is a high risk that the app version might be corrupted. All security applications have their official websites.

If you are looking for a mounting application or similar software, you might need to try a bit harder. Additional security browser extensions might be of service determining which site is safe to download content from. The majority of anti-virus premium versions help you stay protected from malware in disguise as well.

Option 2. The App Was not Installed Correctly

The error occurred during the installation may prevent from uninstalling or reinstalling the application. In that case, you might need to enter Safe Mode and (re)install the program again.

Option 3. Virtual Threats Prevent the Installation

There have been cases when certain types of a trojan or malware altered system files. As a result, users were deprived of installing wanted software. It is especially applicable for security applications. Interestingly, some rogue applications, such as Windows Antivirus Helper also tend to meddle with the app installation settings. [d1] is one of the tools preventing threats from taking over the operating system.

Option 4. Check Memory Cards

These two prolonged micro plates are located parallelly near the fan on the motherboard. If they are damaged or mismatching, you might be unable to install any application at all. In that case, no specific system notification does not appear but after downloading the app, the installation wizard does not appear.

Alternatively, even if you manage to “install” the app, the absence of the program after rebooting suggests that you have to start all over again.