Hello,
The name of the "Deleted" folder must have changed on the server, so trying to move messages there fails.
Easy to check / fix:
- Please long press on the account on the app's main screen.
- Options and folders -> folders
- Let it refresh
- Find [Gmail] and under it either Trash or Bin (or "Deleted" in your language if it's not English)
- Tap this folder's name and choose "Sync with Deleted" from the popup
- Please also check Sent, Drafts and Spam
- Back out of the settings screen and now moving to deleted should work again
Nadia