Hi, as a rule this issue arise after copying one system data to another(e.g. you copied prod to test system). In this case some inconstancy may occur, e.g. one document could exists not in all tables, in your case fagl_splinfo and bkpf.
How to solve it: just find out the last number of specific number range in fagl_splitinfo and assign this number as a Current number in this number range.
For instance, you have dump for DocType SA, number range 01 is assigned to it.
In FAGL_SPLINFO the highest nuber for range 01 is 01008, go to number range configuration and put for number range 01 Number range status=01008