If have installed TWRP and you want to upgrate to the latest firmware using the official procedure, you have to restore the original recovery.img.

1. shutdown the device

2. on the pc extract recovery.img from the update.zip file which contains your current firmware.

   tolino-15.3.0$ unzip update.zip recovery.img
   

3. on the pc run the flash command and keep it waiting

   $ fastboot flash recovery recovery.img 
   < waiting for any device >
   

4. (enter fastboot mode) keep pressed the power up button on the device while inserting the USB cable and in about 25 seconds you should see

   Sending 'recovery' (6474 KB)                       OKAY [  0.245s]
   Writing 'recovery'                                 OKAY [  0.906s]
   Finished. Total time: 1.170s
   

5. reboot the device and now you should be able to upgrade it with the standard procedure