This error may appear during Revise or Relist action if a label of variation specific (such as Color, Size, etc) is different from the one you used before.
For example, initially in Magento a variation label (any attribute of configurable) was Color, but later it was changed to Colour. In accordance with eBay regulations, such a variantion label won’t be accepted.
To resolve this error you can:
- change the initial variation label name in Magento
- stop the listed item and list it as a new one.