I'm trying to manually edgematch some adjacent polygons. When I try to add a vertex to snap it to another vertex on an adjacent polygon, it invariably undoes itself, as shown in this video that I made demonstrating the problem (I couldn't figure out any way to post it here since it is not an image so the best I can do for now is a link).

Bad Snapping

There are 2 vertices in the beginning and I add a third. It is actually removing one of the 2 vertices on the right side and putting the result in the middle. It must be a tolerance of some sort but I tried changing it from 10 pixels to 5 (or 3 or 1) pixels and zooming way in and the problem still occurs (it just becomes more difficult to find the snap point). Is there any other setting I could modify to force the added vertices to snap without moving the other placed vertices?

  • Do you have any topological rules set (geodatabase level or map level) that you think affecting your editing??
    – Learner
    Commented Jan 1, 2016 at 8:04
  • No - the topology rules are simple like "no gaps", and "no overlap". Commented Jan 1, 2016 at 13:55
  • how about Map topology that doesn't participate topology rules ?
    Commented Jan 1, 2016 at 16:13

2 Answers 2


It looks like your snapping tolerance was set to higher number..so decrease the number to like 3 or lower and it should work... You need to play it around and find what it is best for your snapping.

See here http://blogs.esri.com/esri/arcgis/2010/09/20/using-snapping-effectively-in-arcgis-10/

  • there are way more than 10 pixels between the vertices. I tried 3. I even tried 1. Commented Jan 1, 2016 at 0:15
  • I was thinking by looking at the video a few times and I think that there is one thing I can think of is that you need to add the vertex on the red line you have may have no vertex in it. So, if you add the vertex on the red line, then go back to another polygon (light blue) where you were trying to add one and try to add the same vertex you did on the red line. I recalled I did the same thing as you did in the past. So, for example if you have one line that has say 4 vertices on it and the other line has 2 vertices you need to add two more for the 2 vertices to make the snap work.
    Commented Jan 1, 2016 at 4:02
  • If this is too much for you, then maybe Integrate might work for you if you have two polygons you want to be the same. desktop.arcgis.com/en/desktop/latest/tools/…
    Commented Jan 1, 2016 at 4:06
  • I'll look at that. Commented Jan 1, 2016 at 4:43
  • 1
    @PROBERT But integrate tool changes both lines even if rank is high
    – Learner
    Commented Jan 1, 2016 at 8:18

I found the solution interesting (and a little bit funny). I worked with ESRI Support on this yesterday (I finally decided I needed to finish these edits) and the first thing they had me try was to open a blank MXD and copy the parcels layer over into the blank project. I started an EDIT session and everything snapped into place right away! I didn't get a great explanation as to how the MXD affects editing (I assumed it would NOT ... but it DOES!). The analyst said something to the effect of "the project can only keep so many edits". It doesn't make a lot of sense but I suppose it "just is".

I have had trouble running geoprocessing tasks inside of an MXD project file in the past and I always suggest this to people having issues with a tool in the toolbox. I just had not considered that it extended to edit sessions.

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