When saving a key to a Child Sites, Bulk Setting Manager can, under some circumstances, report an “Invalid nonce” error message.

To resolve this issue:

1. Edit the key
2. Create a new text field by drag-and-dropping the “Text Field” from the “Available Fields” box on the right
   
3. Fill in the values of the Text Field
   1. Description: can be any arbitrary value
   2. Name: use the text from the error message after the “Try to use:” part
   3. Value: mainwp-bsm-unverify-nonce
      
4. Save the key

If another type of Nonce error message appears after saving the key, repeat the steps above by adding another Text Field in the key, but in the Name field, use the new error name.