Windows Update downloads but doesn't install: causes and solutions

Updates aren't always straightforward. Sometimes, Windows Update downloads but does not installMany Windows 10 and Windows 11 users are encountering installation errors, endless update loops, or ambiguous messages that don't explain what's happening. If the system also fails to boot, consult [link to relevant documentation]. Repair Windows when it won't start.

In this guide you will find all the common causes and the most effective solutions When Windows Update isn't working properly: from checking the basics (disk space, internet connection, restarts) to repairing system files, using the troubleshooter, installing updates manually, or ultimately reinstalling Windows without losing data.

Why does Windows Update download but not install?

When an update is downloaded but The installation is not completedThis is usually due to one of several categories of problems: software blocking the process, lack of resources, misconfigured services, or corrupted files in the system itself.

In Windows 10 and Windows 11, the update tool depends on multiple internal services, temporary files, and registry keysIf something in that chain fails, you may see installation errors, unclear numerical codes, or generic messages such as "Updates could not be completed."

Some users report that the bug appears out of nowhere, after months of updates working fine, and only after a certain point All new updates get stuck (including major versions like 22H2, 23H2, etc.). In other cases, the problem coincides with hardware changes, installation of third-party antivirus software, or major system modifications.

Furthermore, there are times when even trying to update "outside" —for example, with a Windows 11 ISO downloaded from the Microsoft website— the image itself is not assembled or it throws errors like "There was a problem mounting this file", which shows that the system is more broken than it seems.

Common causes: what can break Windows Update

When Windows Update downloads but doesn't install, there may be multiple culprits acting at the same timeIt is important to understand them in order to apply the appropriate solutions and not proceed blindly.

One of the most frequent causes is incorrect or damaged registration keysIf you have modified the Registry, installed unreliable software, or run scripts that modify Windows services, the values ​​that manage Windows Update may have become corrupted, causing the service to malfunction.

Another very typical cause is that the Windows Update service is stopped or disabledThis service, along with other related services (BITS, cryptography, Windows installer, AppIDSvc, etc.), must be running in the background for the system to download and apply updates correctly.

Problems with the temporary update files located in the SoftwareDistribution folderIf a download has been interrupted or corrupted packages have been stored, the folder itself may prevent new updates from installing normally.

Do not forget the corrupted system filesA disk failure, a power outage, a malware infection, or even a forced shutdown at the wrong time can corrupt critical Windows files involved in the update process.

Finally, several reports indicate that the antivirus and third-party security suites They can interfere with updates, blocking processes, services, or access to key files at the most critical moment of the installation.

Basic checks before complicating your life

Before we delve into advanced commands or deep repair tools, it's worth doing a quick run-through of Basic checks which, in many cases, solve the problem without further ado.

• The first is Restart the systemIt seems obvious, but often there are stuck processes, locked files, or pending changes that can only be resolved with a full restart. After restarting, check for updates again from Settings > Windows Update.
• The second step is to make sure you have a stable internet connectionIn Windows 11, go to Start > Settings > Network & Internet > Wi-Fi (or Ethernet) and check the network status; if it shows as disconnected, reconnect or switch networks, because a slow or unstable connection can leave downloads unfinished.
• It is also essential to verify that there is enough free space on the system disk. Windows needs at least 16 GB on 32-bit systems or 20 GB on 64-bit systems just for the upgrade process, and if you're running low on space, everything will get stuck or fail halfway through.

If your PC has a small drive, Windows may ask you to connect a USB drive to use it as a backup during the installation of a major version. In any case, it's advisable to free up space using tools like Disk Cleanup or the built-in "Disk Cleanup" utility in Settings.

Using the Windows Update Troubleshooter

Windows 10 and Windows 11 include a specific troubleshooter for Windows Update which detects and, in many cases, automatically corrects typical errors: misconfigured services, permissions, paths, etc.

• In Windows 11, go to Start > Settings > System > Troubleshooting > Other troubleshooters Then, within the "Most frequent" section, click Windows Update > Run. Let the wizard perform its analysis and apply the suggested fixes.
• In Windows 10, the process is very similar: Home > Settings > Update & Security > Troubleshooting Then go to “Additional troubleshooters”, select Windows Update and click “Run the troubleshooter”.

When the wizard finishes, it is recommended Restart the system Then, reopen Settings > Windows Update and click on “Check for updates” to see if they are now installing normally.

If any errors persist, you can run the troubleshooter again to detect them. additional failures or continue with the manual methods that we will see below, which are more in-depth but also more effective when the system is severely compromised.

Restart the Windows Update service and related services

One of the most effective methods when Windows Update downloads but doesn't install is Restart the services involved and delete the temporary update foldersYou can do it graphically or using commands.

Let's start with the basics: open the Run window with Windows + R, writes services.msc and press Enter. In the list, locate the “Windows Update” service and check its status and startup type.

Right-click on Windows Update, go to “Properties” and Make sure the startup type is set to “Automatic”If the service is stopped, click "Start"; then click "Apply" and "OK" to save the changes.

If that's not enough, you can completely restart Windows Update and other key services from the Command Prompt. Open cmd as administrator (search for “cmd”, right-click, “Run as administrator”) and stop several services with the commands:

net stop cryptSvc
net stop bits
net stop msiserver
net stop AppIDSvc

Next, rename the folders where Windows stores temporary update files to force a clean install. In the same window, run:

ren C:\Windows\SoftwareDistribution SoftwareDistribution.old
ren C:\Windows\System32\Catroot2 Catroot2.old

Finally, it restarts the suspended services with:

net start cryptSvc
net start bits
net start msiserver
net start AppIDSvc

Optionally, you can use wuauclt.exe /updatenow to force the checking for new updates. This set of steps usually resolves persistent problems with stuck packages or corrupted downloads that prevent installation.

Repair system files with DISM and SFC

If the problem persists after restarting services and deleting temporary files, it is likely that some system file is corruptedThis is where two tools integrated into Windows come into play: DISM and SFC.

DISM (Deployment Image Servicing and Management) is responsible for repair the Windows image which uses the system as a reference, while SFC (System File Checker) checks and repairs individual system files that are corrupt or modified.

To run them, open a Command Prompt as administratorIn the search bar, type "Command Prompt," right-click, and choose "Run as administrator." Once open, type these commands, pressing Enter after each one:

DISM.exe / Online / Cleanup-image / Scanhealth
DISM.exe / Online / Cleanup-image / RestoreHealth

When DISM completes its task (this may take a while, depending on your computer and connection), then run the System File Checker with:

sfc / scannow

It is important wait until the analysis reaches 100% and see if it reports any repairs performed. When it's finished, close the command prompt window, restart your computer, and try the update again from Settings > Windows Update.

In some advanced procedures it is even advisable to run ICACLS C:\Windows\winsxs to check permissions or use additional Microsoft tools, such as the dedicated Windows Update repair tool available at the official shortened URL (for example, downloads like diag_wu).

Manually install updates (KB packages)

If Windows Update keeps failing but you know which update you need, you can always opt for install the standalone package from the Microsoft Update Catalog.

To do this, look at the code of the update that refuses to install; they usually have an identifier like this: KB5017271, KB5016688 or similar. Make a note of the specific number that appears in Windows Update or in the update history.

Next, open your browser and go to the official website of Microsoft Update CatalogIn your search bar, type the KB number (for example, KB5017271) and click Search to see the list of packages available for different versions and architectures.

In the results, locate the entry that corresponds to your version of Windows (10 or 11, Home/Pro, 64-bit, etc.) and click "Download." A window with a link will open; click on it to download. Download the standalone package to your hard drive.

Once you've downloaded the .msu or .cab file, double-click it to launch the installer and follow the instructions. If the manual installation also fails, it's a clear sign that The problem is in the system (not just in Windows Update), so you'll have to persist with DISM, SFC, or more radical steps like system restore.

Restore the system to a previous point

When the problem with Windows Update is recent and you remember that everything was working fine before, a good option is use a system restore point to return to the state prior to the problem.

Restore points, if enabled, allow Windows Save snapshots of critical configuration and files at certain times (driver installation, large updates, etc.), so that you can then return to that situation without touching your personal documents.

To restore, search for "Restore Point" in the Start menu and open the System Restore tool. From there you can See if you have one created. before the updates started failing.

Simply select a point with a date prior to the problem, follow the wizard, and let the system do the rest. Restart and apply the changesIf all goes well, you will return to an environment where Windows Update was working correctly.

Some tutorials suggest combining system restore with uninstalling conflicting updates From Settings > Update & Security > View update history > Uninstall updates, removing the latest one that's causing problems.

When nothing else works: reinstall or reset Windows

If you've tried freeing up disk space, restarting services, using the troubleshooter, running DISM and SFC, manually installing KB updates, and restoring the system, and you're still having problems Windows Update still isn't installing anything.We need to consider emergency measures.

The most common option is reset the computer From the Settings menu. In Windows 10 and 11, go to Start > Settings > Update & Security (or System > Recovery in Windows 11) and click on “Reset this PC”.

From there you can choose if you want keep your personal files (documents, photos, etc.) while Windows is being reinstalled, or a complete cleanup is performed. In both cases, the system reinstalls the operating system components and should leave Windows Update as if it were brand new.

Another possibility, especially if your version of Windows is very outdated or has reached end of service, is to perform a Clean installation using the official Microsoft toolFrom the Windows 10 or Windows 11 website, download the Upgrade Assistant or the Media Creation Tool.

With it you can update in place to the latest compatible version or create a installation usb to start from scratch. However, before formatting or reinstalling, back up your data; a clean install will erase everything on the system partition.

For computers from manufacturers like ASUS, Lenovo, or similar, it's also a good idea to make sure you have the BIOS/UEFI updated and keep your drivers up to date using the tools they provide (MyASUS, Lenovo Vantage, etc.), as some firmware or driver incompatibilities may interfere with Windows updates.

Other common causes: space, hardware, and connection

Beyond internal Windows problems, it's worth reviewing other factors that may explain why updates download but don't finish installing: lack of space, hardware conflicts, or a poor connection.

If the system disk is almost full, the update process will simply There will be no time to unpack and apply the new filesA thorough cleanup with Disk Cleanup, the "Storage Sense" tool, or reliable third-party utilities can make all the difference.

Hardware conflicts (for example, a problematic USB device, a faulty external hard drive, or a component that gives driver errors) can also cause locks during installation restartIn these cases, it's good practice to disconnect all non-essential peripherals and leave only the keyboard, mouse, and monitor; if you suspect a storage issue, you can detect errors in your SSD with SMART commands.

The speed and stability of your internet connection is another key element. If the network is very slow, unstable, or configured for metered use, Downloads may be interrupted or left unfinishedgiving the impression that everything has been downloaded when in reality the package is incomplete.

Finally, make sure your browser and important drivers (graphics, audio, network) are kept up to date through their official channels, because Windows Update does not cover all system components and a very outdated driver can generate side effects during the update process.

When Windows Update downloads but doesn't install, it's usually a sign that Some part of the update chain is damaged or misconfiguredBy following a logical order—from the simplest (restart, space, connection) to the most advanced (DISM, SFC, reinstallation)—you are very likely to get your Windows 10 or Windows 11 to receive patches and new versions normally again, avoiding security problems and keeping the system stable in the long term.