Kaspersky blocks the Steam app

[Slayni]

Today, I ran into a rather frustrating issue. After turning on my computer on March 30, I noticed that Steam didn’t launch automatically as it normally does.

At first, I thought it might just be an autostart glitch, so I tried opening it manually — but nothing happened. The app simply wouldn’t start. I went through all possible fixes: reinstalling Steam, deleting leftover files, and checking system settings, but no luck. Finally, as a last resort, I decided to temporarily disable Kaspersky. To my surprise, Steam launched immediately.

However, the problem persists — every time I restart my PC, I have to turn off Kaspersky to open Steam. This has never happened before, and I have no idea what’s causing it.

You might wonder if I changed anything on March 29 that could have triggered this. The answer is no — I barely used my computer that day. There were no updates for Steam or Windows, and I didn’t tweak any settings, either in my system or in the antivirus software.

One more detail: Poland switched to daylight saving time overnight, from March 29 to 30. Could that have somehow caused a conflict between Kaspersky and Steam? Honestly, I doubt it — but something is definitely wrong, and I don’t know how to fix it.

Additionally, I’m using Kaspersky Plus with active protection and Windows 11 24H2 with the latest updates installed.

If you need more information, screenshots, or video recordings, I’m happy to provide them. This issue is quite frustrating, and I’d really like to solve it — especially since I’ve never encountered anything like this before. I’m also worried that Kaspersky might be blocking more applications than just Steam. For now, everything else seems to be working fine.

Edited Sunday at 07:00 PM by Slayni

[D1G1TAL]

I have same issue, It has nothing to do with Windows 11 24H2 update as I didn't have it installed before the issue started happening, updated my Windows cause I thought that might be the issue but I didn't do anything. Pausing protection will does not allow to launch Steam, only by completely Exiting Kaspersky does Steam start. Started happening around 29th/30th not sure when exactly. 

[Slayni]

33 minutes ago, D1G1TAL said:

I have same issue, It has nothing to do with Windows 11 24H2 update as I didn't have it installed before the issue started happening, updated my Windows cause I thought that might be the issue but I didn't do anything. Pausing protection will does not allow to launch Steam, only by completely Exiting Kaspersky does Steam start. Started happening around 29th/30th not sure when exactly. 

Thank you. Good to know I’m not the only one experiencing this. I hope someone from the Kaspersky team sees this and fixes the issue soon.

[Flood and Flood's wife]

Hello @Slayni & @D1G1TAL, 

Welcome!

Steam is working perfectly (for us). 

1. *Uninstall* Steam.
2. *Uninstall* Kaspersky. 
3. Shutdown the computer using SHUTDOWN, not Restart, power ON by pressing the power button, login.
4. Download a *new* Kaspersky installer: https://www.kaspersky.com/downloads#update-product. 
5. Install Kaspersky, at the end of the install make sure (you're) signed into Kaspersky *application* with the same email address used for (your) MyKaspersky account, so the app & the license/subscription synchronise. 
6. Run a Database update.  
7. Download & Install Steam. 
8. *Again* -> shutdown the computer using SHUTDOWN, not Restart, power ON by pressing the power button, login.
9. Check the original issue, IF it persists log a request with Kaspersky Customer Service, https://support.kaspersky.com/b2c#contacts - select Email OR Chat then fill in the template as shown; include a *detailed history*; Support may request logs, GSI, read: How to generate a report using Get System Info & other data; they will guide you. *Also* @D1G1TAL- select (your) Kaspersky application, from the drop-down-list                                                                

Please share the outcome with the Community, when it's available?

Thank you🙏
Flood🐳+🐋

Edited Monday at 08:40 AM by Flood and Flood's wife
formatting

[Sat_rn]

Hey there, I'm having a very similar issue myself. The apparent cause listed in the problem solver is showing as ntdll.dll crashing.
But the issue started for me around the 26th of March. I assumed it was an OS issue myself, so I reinstalled windows 11, the issue returned a day later. Did another reinstall, but this time blocking windows updates via setting and it was perfectly fine for 4 days.
But then sadly the exact same issue returned last night, found this thread just a bit ago and removed kaspersky and steam immediately started to update and run upon restart.
I can only imagine it's some sort of driver or update kaspersky is pushing breaking something and ntdll.dll is being blamed for it, as I did notice there was a kaspersky update listed in the recent applications via the software.
Not as major perhaps, but I was also throwing the exact same ntdll.dll crash with microsoft common language runtime native compiler around the same time in problem reports, it could be related, but it could also not be.

[Slayni]

22 minutes ago, Sat_rn said:

Hey there, I'm having a very similar issue myself. The apparent cause listed in the problem solver is showing as ntdll.dll crashing.
But the issue started for me around the 26th of March. I assumed it was an OS issue myself, so I reinstalled windows 11, the issue returned a day later. Did another reinstall, but this time blocking windows updates via setting and it was perfectly fine for 4 days.
But then sadly the exact same issue returned last night, found this thread just a bit ago and removed kaspersky and steam immediately started to update and run upon restart.
I can only imagine it's some sort of driver or update kaspersky is pushing breaking something and ntdll.dll is being blamed for it, as I did notice there was a kaspersky update listed in the recent applications via the software.
Not as major perhaps, but I was also throwing the exact same ntdll.dll crash with microsoft common language runtime native compiler around the same time in problem reports, it could be related, but it could also not be.

Good to know, @Sat_rn.

I tried uninstalling both Steam and Kaspersky, as @Flood and Flood's wife suggested earlier, but it didn’t make a difference. The only way to launch Steam is by temporarily disabling Kaspersky’s protection.

Strangely enough, once Steam is running, I can reactivate the antivirus without any issues — the only thing being blocked is the startup process.

PS: I’ve created a ticket and am currently in contact with one of the support agents. I recommend you do the same. Hopefully, we can get this issue resolved quickly.

Edited Tuesday at 11:30 AM by Slayni

[Sat_rn]

That's good to know, as soon I saw this post I immediately unistalled kaspersky and restarted my PC to see steam finally back working, but if all it takes is pausing the protection to launch steam than reactivating it that's a much better solution to unistalling and reinstalling every time the issue pops up. But hopefully they fix this issue that very few seem to be encountering, as it's been a stressful few days since encountering this to say the least.