Occasionally Xero may be missing some Pay Item setup that needs to be resolved to upload data.
The usual cause of this error is that there are Pay Items that do not have a Type defined. They can easily be seen as they have a warning icon next to them (Navigation: Payroll Settings> Pay Items).
The warning icon can be seen below:
Opening it shows the Type field:
The Type (and optionally the Category) must be set and the Pay Item saved:
THESE STEPS MUST BE COMPLETED FOR ALL PAY ITEMS THAT SHOW THE WARNING ICON