Error while updating software Apple Watch

Hello Nezuko_Kh,

Thanks for choosing the Apple Support Communities. If you're having issues updating your Apple Watch, let's try following these steps to see if they help.

Update your Apple Watch - Apple Support

"Need more help with updating?

Try these steps:

1. Make sure that your Apple Watch is connecting properly to its charger. 
2. Restart your Apple Watch.
3. Restart your paired iPhone.
4. Try again to update your Apple Watch.

If the update won't start:

1. Open the Apple Watch app on your iPhone.
2. Tap General > Software Update.
3. Delete the update file.
4. Try again to update your Apple Watch.

Learn what to do if you see 'Cannot Install Update' when updating Apple Watch or if your Apple Watch says you need more available storage to install a watchOS update.

If you installed an iOS or watchOS beta or developer seed

If you installed beta software on your iPhone or Apple Watch, you need to remove the beta profile before you can update to the next major software version:

• Open the Apple Watch app on your iPhone, tap the My Watch tab, then go to General > Profiles. Tap the beta profile that you want to remove, then tap Delete Profile. Enter your iPhone passcode if requested. 
• Open the Settings app on your iPhone, then tap General > Profiles & Device Management. Tap the beta profile that you want to remove, then tap Delete profile. Enter your iPhone passcode if requested. 

After you remove the profiles, restart both devices and check for the update again."

We hope this helps.

Cheers!