If you are encountering an error message stating "Recovery: error validating footer. No vbmeta" on your Samsung M10s phone, you can try the following steps to fix it: 1. Reboot into Recovery Mode: Power off your phone and then press and hold the Volume Up + Power buttons simultaneously until the Samsung logo appears. Release the buttons when you see the Recovery Mode menu. 2. Clear Cache Partition: Use the volume buttons to navigate through the options in Recovery Mode and select "Wipe cache partition." Confirm your selection by pressing the Power button. Once the process is complete, select "Reboot system now." 3. Factory Reset: If clearing the cache partition doesn't resolve the issue, you may need to perform a factory reset. In Recovery Mode, select "Wipe data/factory reset" and confirm your selection. Note that this will erase all data on your device, so make sure to back up any important files beforehand. 4. Flash Stock Firmware: If none of the above steps work, you can try flashing stock firmware on your device using tools like Odin or Samsung Smart Switch. This process requires a computer and specific firmware files for your device model. You can find detailed instructions and firmware files on websites like SamMobile or XDA Developers. It's important to note that flashing firmware carries some risks, so proceed with caution and ensure that you have a backup of your data before attempting it. If you are not comfortable with these steps or if the issue persists, it is recommended to reach out to Samsung support or visit an authorized service center for further assistance.