L'app non stampa le foto

Hi @TitiaVR,
 
Thank you for posting on HP Forums,
Flower_Bud is at your service.
 
As I understand, you’re unable to print from your printer. 
No worries, as I’ll be glad to help you, that said, I’ll need a few more details to dissect your concern & provide an accurate solution:
 
Is your phone updated?
Did you update the firmware? 
Was it working fine earlier? 
 
The HP sprocket app or Sprocket firmware might be outdated, or the Sprocket might be connected to another Apple iOS device.

Make sure your mobile device is connected to the Internet and the Sprocket battery is charged 50% or more.

Make sure your mobile device is updated to Apple iOS 11.2 or later, or the steps in this document will not resolve the issue.
For more information, go to Update the iOS on your iPhone, iPad, or iPod touch (in English) on the Apple Support website.

Turn off the Bluetooth feature on any nearby Apple iOS devices.

On your mobile device, go to the HP sprocket app (in English) in the App Store.

Look for an app update.

If an update displays, tap Update.

If an update option does not display, the app is up-to-date.

Turn on the Sprocket.

On your mobile device, open the Bluetooth settings menu.
Nearby devices display.

Look for your Sprocket in the list.

If the Sprocket displays in the My Devices list, tap the Information icon  , and then tap Forget This Device. Reset your mobile device by turning it off, and then on. Open the Bluetooth settings menu, and then tap your Sprocket from the Other Devices list.

If the Sprocket displays in the Other Devices list, tap it.

If the Sprocket does not display in the list, tap Search or Scan, depending on your mobile device. When the Sprocket displays, tap it.

Open the HP sprocket app.

Tap the Menu icon , tap sprocket, and then tap Printers.
The Sprocket information screen displays.

Look for a Sprocket firmware upgrade.

If a firmware upgrade displays, tap Get Firmware Upgrade, and then follow the on-screen prompts to complete the update.

If a firmware upgrade option does not display, the Sprocket firmware is up-to-date.

You can now connect and send print jobs to your Sprocket.

Click here for the article. 
 
You could also refer to User Guide for more information.
 
Keep me posted how this goes!
Have a wonderful day 🙂
Cheers!