The main cause is a turned-off ASUS service such as AsusCertService, with other causes including missing or mismatched AsIO3_32.sys or AsIO3_64.sys files.
1. Unblock the zip file
One of the most common reasons this issue occurs is because the .zip file you downloaded (containing software that uses AsIO3.sys) is blocked by Windows. This is known to happen with older software builds—until recently, many .zip files downloaded from the official ASUS support website were marked as blocked. To fix this and get around the ‘Can’t open AsIO3.sys‘ error, open the Properties of the .zip file and unblock it before you install anything.
2. Grant yourself full permission for AsIO.sys (if applicable)
If the method above didn’t work and you already have ASUS drivers installed, the AsIO.sys/AsIO3.sys file might already be on your PC—but without the right permissions. This can happen if the file doesn’t have full permission to run when the Windows installer calls it during another ASUS software install. Note: This is often seen on systems with aggressive UAC (User Account Control) settings. To fix this, go to C:\Windows\SysWOW64\drivers\AsIO.sys and adjust its permissions from the Security tab. This has been confirmed to work for many users seeing the ‘Can’t open AsIO3.sys‘ error. Important: This only applies if you previously installed other ASUS software and the AsIO.sys file already exists on your PC. If you’re still seeing the ‘Can’t open AsIO3.sys‘ error, try the next method below.
3. Perform SFC & DISM scans
If you’re still stuck, check whether a corrupted system file is blocking ASUS software from installing (and triggering the ‘Can’t open AsIO3.sys‘ error). You can do this using Windows’ built-in tools: SFC and DISM. System File Checker and Deployment Image Servicing and Management can repair system files that Windows Installer depends on. Start with System File Checker because it runs offline. Follow these steps to deploy an SFC scan. Important: If the SFC window seems to stop responding, do not close it. Let it finish. Note: SFC replaces damaged parts of system files using a local cache. Interrupting it can cause more issues. On older HDDs, this may take an hour or more. When the SFC scan finishes, restart your PC and test if the ‘Can’t open AsIO3.sys‘ error is gone. If not, run a DISM scan next. DISM uses Windows Update to pull clean system files, so you need a stable Internet connection. After both scans, restart your PC and check if the error still appears.
4. Install ASUS Armoury Crate (if applicable)
Even if you’re not a fan of extra utilities, consider installing ASUS Armoury Crate—it often fixes the issue by installing all required components automatically. Note: Armoury Crate is an integration app for ROG and TUF gaming laptops and desktops. It combines features from ROG Gaming Center, AEGIS III, Lighting, and AURA Sync. Installing it helps by pulling all needed dependencies (including the AsIO3.sys dependency). The downside is that it also installs a few ASUS extras, but they’re generally non-intrusive. Important: Only follow this if you’re on a ROG or TUF gaming laptop or desktop.
5. Uninstall the latest Windows Security Update
This problem has also been linked to a bad Windows security update that Microsoft released for some Insider and retail builds on specific ASUS models. If the “Can’t open AsIO3.sys” error started right after Windows installed an update, uninstalling that update may fix it. Important: After uninstalling it, you can hide the update to stop Windows from reinstalling it.
6. Install ASUS AI Suite add-on (if applicable)
If you suspected a bad Windows update above, also check for a pending ASUS AI Suite add-on. Note: ASUS has released add-ons to address this issue for certain models. These are applied using the manual installer from ASUS. AI Suite doesn’t auto-update. To ensure you have the latest components, run the AsusSetup executable from the download package and install any pending add-ons. If the problem is still not fixed or this method doesn’t apply, continue below.
7. Use System Restore to revert the installation of ASUS AI Suite
If the issue started right after updating ASUS AI Suite, you can roll back to a version that didn’t cause this behavior. ASUS only hosts the latest AI Suite build on its site. If you don’t want to use a third-party archive like Oldversion.com, use System Restore. Note: System Restore lets you roll your system back to a previous state. By default, Windows creates restore points at key system events (like app installs and updates). If you didn’t disable System Restore, you should have a restore point from right before the AI Suite update.
8. Uninstall Armoury Crate using a dedicated uninstaller
If you started seeing this after installing or updating ASUS Armoury Crate, you’re not alone—several users reported the same ‘Can’t open AsIO3.sys‘ error tied to a bad Armoury Crate version. To fix it, uninstall the utility using ASUS’s dedicated uninstaller. Important: If you remove Armoury Crate through Programs and Features, leftovers may remain and the error can persist. Use the official uninstaller instead.
9. Enable AsusCertService
Some system optimizer tools can disable the AsusCertService to “save” resources, which can break ASUS apps and trigger the ‘Can’t open AsIO3.sys‘ error. The fix is simple: make sure the Asus Certificate Service is enabled and set to start automatically.
10. Install the latest lighting updates via Aura
Another possible cause is missing lighting updates in one of your ASUS suites. Note: This is a newer dependency required by most ASUS software today. The quickest way to get these components is to use Aura Sync to install them automatically. Aura Sync is now part of Armoury Crate, but you can still install it on its own.
11. Disable Plugins in iCUE Settings (if applicable)
If you use Corsair’s iCUE to sync RGB lighting, it can conflict with ASUS AI Suite and cause ‘Can’t open AsIO3.sys‘. You can usually fix this by opening iCUE Settings and unchecking Enable plugins. After doing this, reboot your PC and test again.
12. Uninstall ASUS Probe (if applicable)
ASUS Probe is a legacy tool that ASUS no longer supports. It’s known to cause compatibility issues with newer ASUS software (AI Suite, Aura Sync, EZ Flash, etc.). Everything it does is already covered by ASUS AI Suite, so there’s no reason to keep it installed.
13. Perform a clean install or repair install
If none of the above worked and you’re still getting “Can’t open AsIO3.sys – Failed with error code 5: Access is denied“, the last resort is to refresh Windows system files. Many users resolved this by doing a full system refresh. You can pick either a clean install or a repair install (in-place upgrade). A clean install wipes everything unless you back up your data (apps, games, personal files, etc.) first. A repair install (in-place upgrade) keeps your personal files, installed apps, and most settings, but it takes a bit longer to complete.
