Fix for Microsoft Bad Update that disrupts WiFi, Cellular, BT for Surface 3 LTE

Posted Posted in Surface


I was a victim of (yet another) bad Microsoft Windows Update for Surface that wreaked havoc with wireless connectivity, cellular, and bluetooth. In addition to the inappropriate Surface Pen driver forced on unsuspecting SP3 users. Surface 3 LTE users also received a nasty surprise.

Symptoms were coming back from hibernate, etc. I’d lose connectivity, WiFi would disappear, cellular would disappear, Bluetooth would disappear. Device manager would cycle through some weird messages when I checked the properties of the  modem adapter and the wifi adapter, ending with Code 38. Bluetooth would be missing. Here’s what the cellular modem driver looked like in Device Manager.


EDIT: Microsoft has posted a KB and link to request a hotfix  The hotfix leads to a requestable fix that is incorrectly labeled as for Surface PRO 3 and not Surface 3 LTE. You’ll get a MSI that you can run to re-install the correct driver.

wrong sku


If you want to fix it manually, steps are below. It’s what I did and it works.


1. Download the driver ZIP file for your device:   Surface 3 LTE ATT  Surface 3 LTE North America Carrier Unlocked  Surface 3 LTE Outside of North America and Y!mobile Japan 


2. Extract the Zip file and make a note of where it is exactly.

3. Open device manager and find System Devices and expand the tree. Scroll down through lots of entries and find Surface CoSAR.

devman coSAR

4. Right Click/press and hold Surface CoSAR to display the Properties window and select Driver, Update Driver.


5. You need to use the force install, Browse your computer, Have disk process. Select Have Disk and then Next.


right click manual

6.  Now you need to navigate to where you extracted the Zip file. You’ll find the needed driver in the \Drivers\MOBB\SurfaceCoSarDriver folder – see screen shot below. (SurfaceCoSARDriver.inf). This is the driver you need to install.

expanded tree

7. After successful install, restart your Surface 3 LTE.

I received this information on the cause being the CoSAR driver from Microsoft Engineering last night. So far, after implementing this fix, things are back to normal. Note, I also rolled back the Marvell wifi driver from .59 to .47 because .47 performs better for me.

If you use my process above, please let me know on Twitter @barbbowman if this resolves your issue.

Microsoft has moved Surface drivers to new URLs

Posted Posted in Surface Surface Pro 3 Surface 3 Surface 3 LTE ATT Surface 3 LTE North America Carrier Unlocked Surface 3 LTE Outside of North America and Y!mobile Japan Surface Pro 2 Surface Pro Surface Pro 4 Surface Book

Recovery from Windows 10 Surface Pro 3 Firmware Update

Posted Posted in Surface


I had a bad experience with the September 29 firmware update for the Surface Pro 3 (bot not as bad as some). Unlike many other folks, my own wireless connectivity and speeds have been great with Windows 10, including using the .193 Marvell wireless driver. That was not the case for many, and a fix for some was to find the older .151 driver on the net and roll back to that. Or to use an external 802.11ac USB adapter (as I mentioned in a previous post).

The 9/29 firmware was unexpected as there had been one on 9/15. I installed it and rebooted and the wireless was MIA. I rebooted a second time and had connectivity, but it was intermittent, slow, and unreliable. Fortunately, I had the older zip files and drivers and was able to re-install the .193 driver and regain my great connectivity.

But this was not the case for others. Reports started appearing on the Surface Answers Forum and customers were reporting loss of wireless, BSOD loops and failed firmware updates in Windows Update history.

I sent emails to Microsoft on the issues and was forwarding threads for several days. The update was pulled on Friday I believe. (Edit 10/5/2015: I’m told it was pulled on 10/1, but if the computer has already pulled it down from WU, it can install anytime up to 10 days later). Customers are reporting getting hosed again but the update was probably already on their system awaiting installation.A couple of bad files were posted for SP3/W10 – both a zip and MSI file – neither of which contain wireless or bluetooth drivers for the SP3. This means there are no drivers posted on Microsoft’s site officially for Surface Pro 3 owners running Windows 10. I’ve always thought (and asked) that Microsoft should post all the drivers and leave older drivers available for those that need them.

Word came down that doing a system restore should get people up again followed by running the MSI to get the firmware/drivers installed, and the Forum owner posted that after doing a system restore, running the MSI file would take care of the issues. This has not been the case for many. And even getting to System Restore has been a problem for some.

Microsoft posted two files for 9/29. I looked inside and there are NO drivers for wireless or bluetooth. As of right now, has two files you should not use:



Here’s the best fix (minus the step to run the MSI) to get out from under the BSOD groundhog day issue if you are still impacted AND can get to System Restore or if you are having issues after this firmware update:

“1.Boot Surface using USB recovery media.  If you do not have recovery media you can download from here:  Once you have recovery media proceed to next steps.
2.Press and hold the volume-down button while you press and release the power button.  When the Surface logo appears release the volume-down button.
3.When prompted select the language and keyboard layout you want.
4.Select Troubleshoot, then Advanced Options, followed by selecting System Restore then select the target operating system.
5.Use a system restore point prior to applying the System Firmware update.  Edit 10/5/2015: Be sure to use a restore point 9/28/2015 or earlier.
6.After moving to an earlier restore point you should boot into Windows.“

If you can’t get to restore or don’t have a restore point, it is going to get ugly. I already see this on the Answers Forum. I don’t have a magic bullet and I don’t know if Microsoft is working over the weekend on this.