When you are trying to install the Avast antivirus on your PC, you might encounter an error message which says that “Avast doesn’t trust Avast Installer”. Once you get this error, you will be unable to install the Avast antivirus application.

The error is also displayed as an error message “There was an error while completing the setup process.”

Mostly, if the Avast installation file is corrupted the error might trigger up. Sometimes, a Windows firewall and an outdated version of the Operating System can also result in this error.  

Top 7 Solutions for Avast Installation Error

There are several solutions to fix the Avast installation error on your computer. Let’s have a look and apply them accordingly.

Solution 1 – Disable Windows Firewall

The Windows Firewall can be responsible for the Avast install error. So, turn it off from the system. To do that, follow these steps:

  1. Press Win + X buttons to open the WinX menu list and select the Control Panel.
  2. On the Control Panel window, go to the Windows Firewall section.
  3. In the Windows Firewall window, click on the Turn Windows Firewall on and off option on the left panel.
  4. On the right window, tick on the Turn off Windows Firewall (Recommended) from both Private network settings and Public network settings sections. 
  5. Click on the Save option. After that, restart the device. 

Solution 2 – Update the Operating System

An older version of the Operating System can also display this error on screen. So, you have to install the latest version of the Operating System. 

  1. Press the Windows Home button and choose the Settings option.
  2. From the Settings window, double-click on the Update & Security section.
  3. Select the Update tab and click on the Check for Updates button to find the available updates. 
  4. If the update is available, then you will get an option Update, click on it. Now the update process will be started. 
  5. Once the update process is completed, the system will automatically restart. 

Solution 3 – Get the Setup Log File 

This is another effective solution that you can try out to resolve the Avast install error on the system. Hence, go through these steps:

  1. When you see the setup error message on the Avast Setup Wizard, then click on the View setup log option to launch the Log Viewer window.
  2. In the Log Viewer window, set the Verbosity settings to the Debug and then click on the Copy to clipboard option. 
  3. Next, open Notepad and click on the Edit and choose Paste to insert the setup log data that you have already copied to the clipboard.
  4. Select the File button and click on the Save As button.
  5. Enter the name of the text file is SetupLog.text. So, anyone can easily find it. Close the Notepad.
  6. Go back to the Log Viewer and click on the Close option. 
  7. After doing this, try to install the Avast antivirus on your PC and see if the error still persists or not. 

Solution 4 – Uninstall the Avast Antivirus and Install It Again

If the installation file is corrupted or missing then you might come across the Avast install error on the system. So, you can remove the Avast antivirus and install it again. Therefore, perform the following steps:

  1. Launch the Control Panel and double-click on the Programs and Features section.
  2. On the Programs and Features window, scroll down the page and locate the Avast antivirus software, select it. After that, click on the Uninstall option. 
  3. Once the uninstallation process is completed, reboot the device and then try to install it again.
  4. So, visit the official website of Avast antivirus and find the latest version of the Avast application.
  5. After finding it, click on the Download button and then install it correctly.
  6. After completing the installation process, restart the system and then check if the error is solved or not. 

Solution 5 –  Make Sure that the Setup File is Uncorrupted

An incomplete download file can cause an Avast installation error. So, check if the setup file is corrupted or not. To know more about it follow these steps:

  1. Right-click on the Avast_(…)_setup_(…).exe and choose the Properties button.
  2. From the Properties window, move to the Digital Signature tab and click on a digital signature and click on the Details button.
  3. If you notice “This Digital Signature is not valid” message, then the setup file is corrupted or missing. 
  4. So, you need to download the Avast setup file from the different computer and install it again. 

Solution 6 – Open the System into Safe Mode

Another easy way by which you can fix this error is to launch the device into safe mode. Here are some steps that you can follow:

  1. Hold the Windows Home key and press the I key together to launch the Settings window.
  2. Go to the Update & Security section and select the Recovery tab. 
  3. From the Recovery tab, click on the Restart now option under the Advanced startup section.
  4. Once the system restarts, the Choose an option window that will appear on the screen. Click on the Troubleshoot button and then select the Advanced options. 
  5. After that, click on the Startup Settings button. 
  6. In the Startup Settings window, click on the Restart option.
  7. After the system restarts, you will get a list of options. Press the F4 key to start the device into safe mode.  
  8. Once you are done with these steps, try to install the Avast antivirus and check to see if the error still occurs or not. 

Solution 7 – Run the System File Checker (SFC) Scan

Running the System File Checker tool can also help you to eliminate the Avast installation error from the device. To run this tool, follow these steps:

  1. Right-click on the Windows Home key and select the Command Prompt(Admin).
  2. Type sfc/scannow in the Command Prompt window and then press the Enter button to run this command.
  3. Once the scanning process is done, restart the computer. 

Hopefully, the above solutions should help you to fix the Avast install error on the system.