# Slab.SetEdgeConnection for multiple surfaces - solution exception error \[SOLVED\] **URL:** \ **Category:** Grasshopper\ **Tags:** solved\ **Created:** [18 November 2023 21:00 UTC](https://femdesign.discourse.group/t/slab-setedgeconnection-for-multiple-surfaces-solution-exception-error-solved/108 "2023-11-18T21:00:49Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![Tomasz\_Gniady](https://dub1.discourse-cdn.com/flex017/user_avatar/femdesign.discourse.group/tomasz_gniady/32/34_2.png) [@Tomasz\_Gniady](https://femdesign.discourse.group/u/Tomasz_Gniady)\ **Post date:** [18 November 2023 21:00 UTC](https://femdesign.discourse.group/t/slab-setedgeconnection-for-multiple-surfaces-solution-exception-error-solved/108/1 "2023-11-18T21:00:49Z")
Hello, At the beginning I’d like to show you my script, which should set up the correct properties to deconstructed plates. ![image](https://europe1.discourse-cdn.com/flex017/uploads/femdesign_api/original/1X/71300cc40a3dd0ee4c6d48c51af5940c611edb03.png) ![image](https://europe1.discourse-cdn.com/flex017/uploads/femdesign_api/original/1X/9b1a6059f534837c377ad81474c2e9426bb5bc76.png) There is an error “Solution exception: object reference not set to an instance of an object”. Any suggestion why it appears and how to fix it? ---
**Author:** ![MarcoPelle](https://dub1.discourse-cdn.com/flex017/user_avatar/femdesign.discourse.group/marcopelle/32/6_2.png) [@MarcoPelle](https://femdesign.discourse.group/u/MarcoPelle)\ **Post date:** [20 November 2023 10:05 UTC](https://femdesign.discourse.group/t/slab-setedgeconnection-for-multiple-surfaces-solution-exception-error-solved/108/2 "2023-11-20T10:05:47Z")
@Tomasz_Gniady From the provided picture, I would assume that you need to “graft” the Slab input ---
**Author:** ![MarcoPelle](https://dub1.discourse-cdn.com/flex017/user_avatar/femdesign.discourse.group/marcopelle/32/6_2.png) [@MarcoPelle](https://femdesign.discourse.group/u/MarcoPelle)\ **Post date:** [20 November 2023 10:13 UTC](https://femdesign.discourse.group/t/slab-setedgeconnection-for-multiple-surfaces-solution-exception-error-solved/108/3 "2023-11-20T10:13:20Z")
@Tomasz_Gniady You can see my “data structure” in the picture below. ![image](https://europe1.discourse-cdn.com/flex017/uploads/femdesign_api/original/1X/3260e13b10517baeb8569be704da51f828d28264.png) ---
**Author:** ![Tomasz\_Gniady](https://dub1.discourse-cdn.com/flex017/user_avatar/femdesign.discourse.group/tomasz_gniady/32/34_2.png) [@Tomasz\_Gniady](https://femdesign.discourse.group/u/Tomasz_Gniady)\ **Post date:** [20 November 2023 10:32 UTC](https://femdesign.discourse.group/t/slab-setedgeconnection-for-multiple-surfaces-solution-exception-error-solved/108/4 "2023-11-20T10:32:24Z")
I’ve tried this one, erorr still appears. ![image](https://europe1.discourse-cdn.com/flex017/uploads/femdesign_api/original/1X/af0cd61663a7b7d0da86649d14a8e231304c5b4d.png) Please find script and model attached, maybe it will be helpful. [EdgeConnForMultipleSurfaces\_error\_replication.zip](https://femdesign.discourse.group/uploads/short-url/8uxnmwbnSeujl3zPCqe618Rig5e.zip) (5.8 MB) ---
**Author:** ![MarcoPelle](https://dub1.discourse-cdn.com/flex017/user_avatar/femdesign.discourse.group/marcopelle/32/6_2.png) [@MarcoPelle](https://femdesign.discourse.group/u/MarcoPelle)\ **Post date:** [20 November 2023 11:16 UTC](https://femdesign.discourse.group/t/slab-setedgeconnection-for-multiple-surfaces-solution-exception-error-solved/108/5 "2023-11-20T11:16:36Z")
@Turez Looks like that you were setting some “nulls” edge connections and indexes and the component doesn’t like it 🙂 . Below, a proposed solution that should work. [EdgeConnForMultipleSurfaces\_error\_replication\_SOLVED.gh](https://femdesign.discourse.group/uploads/short-url/nBBxWPJi4MOgAuAtsgKthgGPbMH.gh) (17.4 KB) I am going to slightly improve the “set edge connection” as it does not look fully user friendly ---
**Author:** ![Tomasz\_Gniady](https://dub1.discourse-cdn.com/flex017/user_avatar/femdesign.discourse.group/tomasz_gniady/32/34_2.png) [@Tomasz\_Gniady](https://femdesign.discourse.group/u/Tomasz_Gniady)\ **Post date:** [20 November 2023 11:50 UTC](https://femdesign.discourse.group/t/slab-setedgeconnection-for-multiple-surfaces-solution-exception-error-solved/108/6 "2023-11-20T11:50:08Z")
@MarcoPelle Great input as always from your side. Yeah for component it works, but overall order of the edges looks messy and some of them are missing: ![image](https://europe1.discourse-cdn.com/flex017/uploads/femdesign_api/original/1X/470a03a5eeeb2b2a0387d019aabf340e14925be1.png) I gues, that without “nulls” edges are randomly prescribed to the surface. ---
**Author:** ![MarcoPelle](https://dub1.discourse-cdn.com/flex017/user_avatar/femdesign.discourse.group/marcopelle/32/6_2.png) [@MarcoPelle](https://femdesign.discourse.group/u/MarcoPelle)\ **Post date:** [20 November 2023 13:43 UTC](https://femdesign.discourse.group/t/slab-setedgeconnection-for-multiple-surfaces-solution-exception-error-solved/108/7 "2023-11-20T13:43:02Z")
@Tomasz_Gniady have a look at the following script [EdgeConnForMultipleSurfaces\_error\_replication\_SOLVED\_2.gh](https://femdesign.discourse.group/uploads/short-url/91j7eT1FDNLwqEteBJVlZwWs3pE.gh) (16.8 KB) Can you just “setEdgeConnection” without creating a new one? There is a Bug in constructing the surface again which changes the order of the edge ---
**Author:** ![Tomasz\_Gniady](https://dub1.discourse-cdn.com/flex017/user_avatar/femdesign.discourse.group/tomasz_gniady/32/34_2.png) [@Tomasz\_Gniady](https://femdesign.discourse.group/u/Tomasz_Gniady)\ **Post date:** [20 November 2023 14:12 UTC](https://femdesign.discourse.group/t/slab-setedgeconnection-for-multiple-surfaces-solution-exception-error-solved/108/8 "2023-11-20T14:12:59Z")
Yes, in this case is even better for me to not creating a new one. Thanks a lot! It’ll be nice to fix this bug, as I suppose there will be some case, where creatring a new one will be necessary 🙂