Heads up for anyone using a TI-84 Plus CE with Windows 11: since around April 2026, some Windows 11 systems may no longer be able to connect to the calculator through TI Connect CE because Windows blocks the TI driver.

The error I’m seeing in Device Manager is:



This is not the usual “bad cable” or “TI Connect can’t find my calculator” issue. In this case, Windows detects that there is a driver involved, but refuses to load it because of Application Control policy enforcement.

What this means in practice:

• TI Connect CE cannot see the calculator.
  
• Replugging the calculator does not fix it.
  
• The calculator itself may be fine.
  
• The .8xp files may be fine.
  
• The same program can work in CEmu/emulator.
  
• The failure is between Windows 11 and the TI-84 CE USB driver.
  

I tried the usual troubleshooting path: different connection attempts, checking Device Manager, and confirming that the calculator program itself works in the emulator. The blocker appears to be Windows refusing the TI driver, not the calculator or the transfer file.

Until TI releases an updated Windows driver that complies with current Windows security requirements, affected Windows 11 users may be stuck. Possible workarounds are using a Mac/Linux machine, another computer that still allows the driver, or emulator-only testing.

If anyone else is seeing the same Code 39 / Application Control policy has blocked this file error, please post your Windows version, TI Connect CE version, and calculator model/OS version. It would be useful to know how widespread this is.

This seems like it's a limitation imposed by the admin of your computer, not Windows. Application control is described as a security tool for domain admins and for most users who administer their own computers it won't be enabled.

Nah, this problem has been reported all over, here, tiplanet, Reddit, and other social media, so I assume it's now the default policy after having applied the April 2026 update.
TI is aware, but they have yet to fix it...

For now just install WinUSB and use webtilp. It's better, anyways.

Maybe this will save some people from accidentally updating to 5.8.5 :)

You don't actually have to "install" WinUSB, it's what windows comes with.

So this driver issue now doesn't matter if you are using WebTILP it will still work (or well it would become the only working alternative until it fixes it): you need to use Zadig to rebind the calc driver to be "WinUSB" (click the options menu and choose List All Devices, then pick the calc on the left then WinUSB on the right, then the button to install/update it). Then it will work fine.

(that's what I meant by install WinUSB. But you explained it much better)

yeah

I've opened a ticket with TI because of this.
This was their reply:

any idea when this will be fixed?

When TI fixes it.

Hi there, I have just purchased a TI 84 plus CE Python. Having the issue you are explaining. I am not computer savvy or calculators for that matter! I am having trouble even it seems to activate my account, if that is even a thing? I can log in, have downloaded the software that cannot be read, tried to activate it. I suppose if Windows will not recognise it there is no way I can activate it? I am at a loss as to what to do. Tried the contact for New Zealand today, it gave a site www.bit/ly. something I will have to look it up. Would someone out there be so kind as to help explain if there is a way I can still get these apps to work, or how on earth I figure out what I am doing please? Sorry to be such a twit!!

What OS are you running? If you are running Windows 11, Windows may sometimes refuse the TI USB driver. Microsoft says App Control for Business can control what runs on your Windows devices by setting policies that specify whether a driver or application is trusted. So TI-Connet CE would have to be updated to fit Microsoft's Standards for it to be fixed, as mentioned in the post

So I guess you would have to wait until TI updates the Software. The latest version is currently 6.0.4, which was released on June 30, 2026. I don't know if it is fixed in this version, but that is the latest one as of 7/17/26.

v6.0.4 from a few days ago unfortunately doesn't fix it, no.
I've asked TI again to see if they have any news about this.

In the meantime, WebTILP works but does require a bit of driver setup using Zadig (make the calculator bound to WebUSB instead of TI's driver) which isn't very beginner-friendly... thanks Microsoft.

Oh, alright, interestingly, the Mac Version of TI-Connect CE is still on version v6.0.3.



Are you gonna show what they said if TI responds

I'm suffering this as well. Replying so I can monitor the situation.

TI Connect CE has been updated to 6.0.4 on MacOS, but it isn't Apple Silicon still. It's intel-based so I'm guessing TI might not update it before Apple kills off Rosetta.

I got a reply from the ticket I put in to TI. The work around did work to allow me to get things connected in the short term.

Thank you for contacting Texas Instruments,

I understand that our drivers are being blocked. We apologize for any inconvenience this issue may have caused.

We have identified that this issue is caused by a recent Windows 11 security update that blocks certain third-party drivers. While we are actively working on a permanent solution, we can offer the following temporary workaround in the meantime.

Please be advised: The steps below involve disabling Windows driver signature enforcement, which temporarily removes essential security protections and may leave your PC vulnerable. Please make sure to re-enable Driver Signature Enforcement immediately after completing the process.

Workaround Steps:

1. Click the Windows Start button, then click the Power icon.
2. Press and hold the [Shift] key on your keyboard and, while holding it, click Restart. Continue holding [Shift] until a blue screen appears.
3. On the blue screen, click Troubleshoot, then click Advanced Options.
4. Click Startup Settings. If you do not see this option, click "See more recovery options" at the bottom of the screen. Then click the Restart button in the lower right corner.
5. Your computer will reboot and display a list of startup options numbered 1–9. Press the [7] key to select "Disable Driver Signature Enforcement."

Once your computer has restarted, please open TI Connect CE and attempt to connect your calculator again. It should now be detected.

Please remember to re-enable Driver Signature Enforcement after completing the above steps to restore your system's security protections.

If the issue persists or you have any other questions, please feel free to reply to this email, and we will be glad to help.

Warmest regards,
Gustavo Garzón
CSC Specialist
Texas Instruments Education Technology
For details on how to contact us and our working hours: https://education.ti.com/en/contact-us

So it does look like they ARE gonna fix the issue in the future 😁

Any updates on this issue? Just recently tried tinkering with this Calc I found and fell victim to it ☹️