Ok, so this is a brain scratcher. I’ve never seen this error before. I just upgraded to 7.0.10. I have several 7-segment displays. One of them keeps giving me this error every time I run the ERC. I’ve moved it 4 times. I’ve reset the grid 3 times. The other 5 in the schematic are fine. I’ve been using KiCad since version 5 so I’m not a noob. Any Ideas?
the “symbol and wires are on grid” check was new introduced with v7, so it’s not astonishing that you didn’t see this errorbefore
the check does exactly what the name (and the error message) says: checking if all wire-ends and all symbol pins (the connection points of the pins) are positioned exactly on the current choosen grid
so work with standard 0,05" grid
to fix your schematic the fast way: box-select the problematic symbol/wires -->RMB-click–>context menu–> Alaign elements to grid
rerun ERC again (don’t change grid between the alignment process and the ERC run)
one remark: to get a better help you should attach not only a picture/pdf file, but also help the complete archived project (maybe a little bit cleaned - without backup files for instance).