A Bluetooth driver error means Windows can see the Bluetooth hardware but cannot load the software that drives it. Device Manager usually shows a yellow warning triangle on the adapter, and the fix is a clean driver reinstall, with the right driver coming from the PC maker rather than a generic download.
Fix it, in order
Read the exact error in Device Manager. Right-click Start, select Device Manager, expand Bluetooth, right-click the adapter, and select Properties. The Device status box on the General tab gives the error code, such as Code 43, Code 10, or Code 28, and that code decides which fix to try first.
Run the Bluetooth troubleshooter. Open Settings, System, Troubleshoot, Other troubleshooters, and select Run next to Bluetooth. It checks the driver state and the support service, and can apply basic fixes itself.
Update the driver. In Device Manager, right-click the adapter and select Update driver, then Search automatically for drivers. If Windows says the best driver is already installed, that only means it found nothing newer, not that the installed driver is good.
Uninstall the driver and restart. Right-click the adapter, select Uninstall device, and check Attempt to remove the driver for this device if the box appears. Restart the PC and let Windows reinstall the driver from scratch.
Install the driver from the PC maker. Go to the support site for the laptop or motherboard maker, search for your exact model, and download the Bluetooth or wireless driver package for your Windows version. On most laptops Bluetooth and Wi-Fi share one driver package, so install the whole wireless package.
Roll back if the error started after an update. In Device Manager, open the adapter Properties, open the Driver tab, and select Roll Back Driver. A Windows Update or a driver update that broke a working adapter is one of the most common causes.
Check the Bluetooth services. Press Win + R, type services.msc, and press Enter. Make sure Bluetooth Support Service, Bluetooth Audio Gateway Service, and Bluetooth User Support Service are running, and restart any that are stopped.
Do not download drivers from driver updater sites or search result ads. The only safe sources are Windows Update and the PC or motherboard maker's own support site, and a wrong driver can make the error worse.
If it still happens
If every driver reinstall ends with the same error, check whether the adapter also fails after a cold shutdown with Shift plus Shut down, which resets the radio hardware. A driver error that survives a clean manufacturer install and a cold boot points to the wireless card itself, and on many laptops that card is a replaceable module.
Common questions
What does the yellow triangle on the Bluetooth adapter mean? Windows detected the hardware but the driver reported a problem. Open Properties and read the Device status box for the exact code, then match the fix to that code.
Windows says the best driver is already installed. Is the driver fine? Not necessarily. That message only means Windows Update has nothing newer. The installed driver can still be corrupted, so uninstall it and install the maker's package instead.
The error says the driver is unavailable. What does that mean? Windows cannot find a working driver for the adapter at all. Reinstall the driver from the PC maker's site, and if the adapter is missing from Device Manager entirely, check the page on Bluetooth missing from Settings.