Troubleshooting Steps to Fix Dell Latitude 5420 Laptop HTTP Boot Error
1. Uninstall all USB drives or media devices that may be plugged into the device.
2. To enter the Bios menu, power on your device and repeatedly click F2 button.
3. Once in the Bios menu, click on Boot Configuration. Ensure that Windows Boot Manager is first in the Boot Sequence. See image below for example. You can use the up and down arrows to change the sequence. In addition, check off the UEFI HTTPs Boot.
4. Hit Apply Changes if you changed anything. Click OK to confirm.
5. Click Exit. The computer may run a Prepare Automatic Repair. You may be required to click a Restart option. After restarting, your device should boot up regularly.