To solve a persistent Error 50 in Mainland, please try the following: 
1. Go into the Super Manager menu (or Equipment or Briefcase or Elemental Packs), then go into the list of Mainland mines, tap the checklist next to the mine that is frozen and tap "end Mine"

2. While connected to the internet, if you use one of these ways to enter the Mainland's list of mines (so the main entrance, Travel icon, Briefcases or Equip menu, etc.) BUT you cannot enter, try turning off wifi/cellular data, then click on the mine and just turn back on wifi/cellular data once in the Mainland mine.

If that doesn't work, please try the following:

- Open the game

- Enter the Super Manager Tower from the map

- Click on the Mainland tab (last tab to the right)

- Scroll up to the first mine

- Slowly scroll down the list of the mines you already finished

- Once you approach the current mine, try entering it

If this does not work, please repeat the steps before contacting support. Please let us know which steps you have tried when you message us!