The transfer statuses of the article groups to be merged do not match.
Explanation:
The attribute HeaderInSpec1..X regulates whether the attribute with the corresponding value and unit is to be placed in the article table or at the bottom of the specification field.
If articles are merged into one group and the articles have different values for HeaderInSpec for one or more attributes, this error message will be displayed.
After all, a feature cannot be for one article in the specification and for another article from the same article group in the article table.
Solution:
Make sure that the same value for HeaderInSpec is assigned to all articles within an article group. This can be done at your discretion via EZ-catalog or in the import file.