This scanning problem can appear on both free and paid editions of Avast antivirus. You may see the Avast smart scan stuck at 99 or, sometimes, after the scan is complete. Before learning how to solve this error, we should know the reasons.

Why is Avast antivirus unable to scan certain files?

If your Avast Antivirus, Premium Security, or Ultimate edition show unable to scan message, it may have the following reasons:

Corrupted files: Some files may be corrupted. So, Avast antivirus cannot read them properly. Password-protected files: You cannot scan any password-protected files or folders using AV, as no other persons or companies know these passwords. Outdated version of AV: If you are using a very old version of Avast security, it may be the reason you find Avast smart scan stuck at 90, so it’s time to take action, as described below. Outdated OS: Is your operating system very old? If yes, it may not be fully compatible with the recent versions of Avast. Corrupted antivirus software: It is also possible that your antivirus installation files have been corrupted. So it cannot scan all files properly. Conflict with other software: If you have more than one Antivirus program installed on your PC, interference may happen in their operations.

What can I do if Avast security is unable to scan?

Before going through the main solutions, we suggest you take some steps. These may save you time in troubleshooting this problem:

Update Windows to the latest version. Repair corrupted system files by running the SFC command. If there are unscannable files that are password-protected, remove that protection if possible.

1. Exclude file

You should expect that some files cannot be scanned. If there are such files, it doesn’t mean these are threats. Some of them can be your system file or files related to the software you are using. Excluding these items from scanning will help to avoid seeing unwanted unable-to-scan messages.

2. Update Avast

Updating the Avast antivirus to the latest version will solve any incompatibility issues. If compatibility is the reason you were getting the error, it will help to fix Avast security’s inability to scan issue.

3. Uninstall the second antivirus

As other AV programs can interrupt the scanning process of Avast, it is safe to uninstall them. Then, see if Avast security is still unable to scan some files or not. SPONSORED

4. Verify all required background services are active

4.1 Using services windows

4.2 Using system configuration

Sometimes, some PC optimization software or you may have disabled some required services that Avast uses to operate properly. Re-enabling them will help to get rid of any related problems.

5. Re-install Avast

Re-installing the Avast security program will help if the previous installation files are corrupted. After installing the fresh copy, you should no longer encounter unable to scan problem with Avast AV. Following the above methods will surely help. Also, these would work if you find the Avast One smart scan not working. However, if you still face the issue or want to try other programs, you can do it. For this, we suggest you check out these best Antivirus programs. This article has shown how to fix Avast Security unable to scan problems. If you know other better ways to troubleshoot this problem, feel free to let us know in the comment box.

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