Kaspersky says databases are corrupted and updates keep failing

Fix it now

This is a documented Kaspersky error shown in the Database Update window, and Kaspersky publishes one procedure for it: uninstall the application while keeping the licence information, restart, install it again, and activate. There is no supported folder to delete and no cache to clear.

1. Run the update once more first. A single clean run costs a minute and sometimes rewrites the damaged set.
2. Download the installer for the exact Kaspersky product you have – Standard, Plus, Premium, or the older Internet Security, Anti-Virus, Total Security or Small Office Security – before you remove anything.
3. Uninstall the application, and tick the option to keep your licence or subscription information when the uninstaller offers it.
4. Restart the computer.
5. Run the installer you downloaded and let it complete.
6. Let the application activate itself, or enter your code manually if it does not, then run a full database update and leave it alone until it finishes.

Keeping the licence information during removal is the step that makes this safe. Do not skip the checkbox and then discover you cannot find the code.

If the update completes and the database date is current, you are done. If not, the next section covers what else produces this and what Kaspersky does not publish a fix for.

Why it happens

The message means the local database set failed its own integrity check. The application will not load a database it cannot verify, so it stops using it, and every subsequent update attempt fails against the same files. Nothing has been detected and nothing is wrong with your licence.

It is worth being clear about what is and is not documented here, because this error attracts more invented procedure than almost any other. Kaspersky publishes the error and publishes one remedy: reinstall, keeping the licence. It does not publish a folder path to delete, a cache to clear, a rollback to a previous database set, or a self-defence toggle to switch off first. Articles that hand you a path under ProgramData and tell you to disable self-defence are describing something they worked out rather than something Kaspersky supports, and if it goes wrong you are reinstalling anyway – which was the documented fix in the first place.

What does make sense to check before you reinstall is everything that damages files in general. A database update interrupted by a power cut, a sleep event or a dropped connection. A system drive that filled up mid-write. A disk with bad sectors. A second security product or a disk-cleaning tool that quarantined or deleted files it did not recognise. All of those produce a corrupted set, and all of them will produce another one after the reinstall if you do not deal with them.

Full reference

Kaspersky’s documented procedure, in order

1. Download the installer for your specific Kaspersky product. The published list covers Standard, Plus, Premium, Internet Security, Anti-Virus, Total Security and Small Office Security.
2. Uninstall the current application using Kaspersky’s removal instructions, ticking the option to keep licence or subscription information during removal.
3. Restart the computer.
4. Run the installer and follow the installation steps for that product.
5. Let the application activate automatically, or activate it by hand using the product’s activation guide.
6. If the corruption persists after all of that, contact Kaspersky Customer Service.

The order matters in one specific way: download the installer before you remove the product. A machine with no antivirus and no installer, on a connection that then fails, is a worse position than the one you started in.

What the companion codes are and are not

12017 is the only one carrying information, and what it carries is consistent with the whole picture: a transfer that stopped before it finished. If you see it repeatedly rather than once, look at the connection and at anything that suspends the machine mid-download before you look at Kaspersky.

Protecting the machine while you work

• Between uninstalling Kaspersky and finishing the reinstall, Windows brings Microsoft Defender back automatically. That is real protection, and it costs nothing.
• Do the work in one sitting rather than leaving the machine part-done overnight.
• Be conservative about what you download while the database set is broken or absent.
• Do not install a second antivirus “just for now”. That is how a one-hour job becomes a weekend.
• Keep the activation code somewhere you can reach it, even though the uninstaller should preserve it.

Why the first update after a reinstall takes so long

It fetches a complete set rather than a difference, and on a slow connection that is a meaningful wait. Leave it running on a wired or otherwise stable link and do not interrupt it, because interruption during a database write is one of the ways you got here. It is also the reason to do this at a time when the machine can be left alone rather than at the end of the day.

If it comes back

1. Note how long the machine ran cleanly before it returned. A pattern of days points at something on a schedule.
2. Check what runs on that schedule: cleaning tools, backup software, disk optimisers and second security products are the usual suspects.
3. Check the Windows System log for disk and storage warnings around the times it broke.
4. Test the drive with the manufacturer’s tool rather than assuming chkdsk’s silence is a clean bill of health.
5. If nothing explains it, contact Kaspersky Customer Service. That is the published escalation and there is no third reinstall worth doing.

None of this is a licensing problem. A valid licence does not prevent database corruption and a larger one does not repair it. If anyone tells you an upgrade is the answer to this message, they are guessing.

Every code this article covers

Confirm the fix worked

1. The update task completes and the database date shown is current.
2. The main window reports protection as active with no outstanding issues.
3. A quick scan completes without reporting a database problem.
4. The licence is still shown as active after the reinstall, with the correct expiry date.
5. Restart the machine and run the update once more, so you know the set survives a reboot.

Questions people ask about this