Why can’t I send files via the laptop’s bluetooth

EDIT: I just did this a second time because it happened again, and it doesn't fully work. I'm not sure why it worked for me the first time I tried it. Apparently installing the Intel Bluetooth driver and restarting isn't enough. I don't know what to do next.

Solution for anyone who encounters this problem: This worked for me at least.

i.) Go into your device manager (on Windows 10, type "device manager" in the start menu and it should show up):

ii.) Once there, depending on whether or not your Bluetooth device driver had disconnected (for whatever reason), you might need to go to "View" and select "Show Hidden Devices".

iii.) You should be able to see your Bluetooth drivers now (if not, unfortunately I'm not sure what to do, your drivers might already have been uninstalled accidentally and you might just be able to skip to step iv, but no guarantee). Open the "Bluetooth" dropdown menu and uninstall each driver by right clicking it and selecting "uninstall":

iv.) Once all your Bluetooth drivers have been uninstalled, download and install a new Bluetooth driver, such as this one from Intel (make sure you choose the correct version for your system; 32/64-bit). Install it by double-clicking the .exe file you just downloaded and follow the instructions.

iv.i) (Optional) For good measure, restart your system in between uninstalling your Bluetooth drivers, and installing the new ones. Windows might automatically detect that the drivers are missing and reinstall them itself. It didn't do this for me, which is hwy I had to download the drivers manually.

v.) Once the new drivers have been installed, restart your system. For me, when I checked my device drivers after restarting, the newly installed Bluetooth drivers were there, and working properly. Knowing how sporadic Windows 10 seems to be, this could differ on your system, in which case leave a comment explaining the problems you've encountered and I'll be happy to assist (even though I'm not actually an IT guy, I just got lucky in fixing my own problem I suppose).

If you're asking what has changed, then Windows itself has changed, to protect you against unwanted files. Microsoft has now published the procedure they impose in the article Share files over Bluetooth, which is exactly as you have observed.

Should you wish to avoid this procedure, your options are to either use email or a third-party application.

Examples of such applications are Join (free) or Pushbullet (limited free account).

Another possibility is to install on the phone an application for an SSH server, for example on Android the SSHDroid, then use for example WinSCP on the PC to directly access the folder on the phone from the PC.