topic Re: Merge model builder does not preserve Field Map setting in ArcGIS Pro Questions

Merge model builder does not preserve Field Map setting

LucileFayolle — Fri, 08 Oct 2021 03:44:47 GMT

ArcGIS 2.8.3

In my model builder I use the merge tool with the field map to reconciliate the fields of the two data source. Problem is: When I set the field map, validate by clicking ok and reopen the tool, if I click to change anything in the tool, the field map reset. Even if I change the output field name, the field map reset.

It look exactly like the bug that happened with the Append tool in 2019 (See post about it and esri answer)

I wonder if it is a common issue or it may be related to my model. I consider using the Append tool to replace this or even some Calculate field, but would rather keep the Merge.

Thank you

Re: Merge model builder does not preserve Field Map setting

SarahHartholt — Tue, 02 Nov 2021 20:17:22 GMT

I am currently experiencing the same thing. I started creating a set of models a few months ago. Some of the input data has changed so I've had to re-map fields in my Merge tool. I add and map 9 new fields, click ok to accept the changes and run my model. The GP tool following the Merge tool fails and says that a field does not exist within the table (ERROR 000728). When I open the merge tool in the model again the 9 fields that I mapped are no longer there.

Re: Merge model builder does not preserve Field Map setting

PhilipMarty — Tue, 09 Nov 2021 20:35:18 GMT

Is this a logged bug? This is so frustrating. I have the exact same issue.

Any way to escalate it?

Re: Merge model builder does not preserve Field Map setting

aynow — Fri, 29 Apr 2022 13:00:58 GMT

I had the a similar issue when using Merge with inline variable substitution in files paths. The only workaround I could find was to replace the variables with hard-coded paths (unfortunately).

Re: Merge model builder does not preserve Field Map setting

DaveronSmith — Fri, 17 Feb 2023 12:41:22 GMT

Still an issue, significantly impacts workflows. (ArcPro 3.0.4)

Re: Merge model builder does not preserve Field Map setting

CMorneau — Mon, 06 May 2024 22:35:15 GMT

Our team just recently upgraded to Pro 3.2.2. The upgrade appears to have messed up something with the Merge process within one of my Model Builder tools. My Field Map in Merge was setup so that a couple of fields would be positioned a certain way in the model's output table. The upgrade appears to have caused the Merge Field Map to be reset. I understand that can happen. But when I edit the model & reposition the fields to my liking, the setup no longer persists. I've tried a bunch of fixes, including replacing the Merge process altogether with a new instance of Merge. Exposing the Field Map variable in the model, even setting it as a parameter, doesn't preserve my fields order. Am I missing something, or is this yet another Field Map bug?

Re: Merge model builder does not preserve Field Map setting

AaronLowe — Fri, 26 Jul 2024 17:31:45 GMT

I'm seeing this same behavior in Pro 3.2.3. What's weird is that sometimes the settings will stick for a while and then they'll disappear randomly when I'm working on another part of my model.

Re: Merge model builder does not preserve Field Map setting

Kaksak — Wed, 28 Aug 2024 16:58:19 GMT

Still having issues as described above using Merge in Model Builder with ArcGIS Pro 3.3.1. Field map re-sets unexpectedly and is not saving changes, causing lots of headaches in models.

Re: Merge model builder does not preserve Field Map setting

AaronLowe — Wed, 28 Aug 2024 17:34:52 GMT

Yeah, super frustrating. I ended up adding a common field in all of my inputs so that it merged without requiring a customized mapping.

Re: Merge model builder does not preserve Field Map setting

MandP — Thu, 05 Sep 2024 05:01:36 GMT

I came across this issue today which is wild it still hasn't been fixed. However I've found a solution!

Create a variable Field Map from the Export Features tool like below.

By doing this the values seem to persist between sessions. I haven't tested this with other tools using Field Map but presume the same would work.

Re: Merge model builder does not preserve Field Map setting

EApolinar — Fri, 11 Oct 2024 13:32:54 GMT

This is very interesting, however it does not seem to work for me.

Im using the Field Map for the Append tool in a Model on ArcGIS Pro 3.1.0 and can't find a way for it to remember the Field Mapping. Everytime I close the tool/variable, it goes back to blanc.

Re: Merge model builder does not preserve Field Map setting

AFangman — Thu, 07 Nov 2024 02:43:16 GMT

3.2.2 here. I have the same issue with the Merge not remembering my Field Map setup.

Re: Merge model builder does not preserve Field Map setting

RachelPinkston2 — Mon, 21 Apr 2025 17:13:31 GMT

I'm still on Pro 3.2.2, I have not upgraded to 3.4.x yet, so I'm not sure if this issue has been fixed in the more recent updates, but I wanted to share that ManP's solution above, worked for me. Creating a field map variable retains the field mapping between sessions. Thanks.

Re: Merge model builder does not preserve Field Map setting

CMorneau — Sat, 10 May 2025 04:30:28 GMT

Hello to All. Our team upgraded to Pro 3.4.3 on all our workstations about a month or so ago. I tested my model that had the Merge tool Field Map issue, & it works fine now. My settings persist from session to session, as they did once before. I brought this issue to the attention of Esri's Shitij Mehta at the UC last year & she agreed that it sounded like a bug. She said that she & her team would look into it. I believe I saw somewhere that the bug was documented. Bottom line - Esri appears to have fixed the issue.

Always great to connect with the right person at the UC & then see the issue ultimately get resolved after having that type of interaction. Shitij is one of my Esri heroes & I always make it a point to tell her so. Good for a few laughs, anyway. Good luck with your models that have the Merge tool. Please chime in if upgrading to Pro 3.4.3 resolved your issue.

Re: Merge model builder does not preserve Field Map setting

NevilleWilson_Everick — Fri, 10 Oct 2025 06:11:06 GMT

this is Still a Bug in 3.3 as well

Re: Merge model builder does not preserve Field Map setting

NevilleWilson_Everick — Tue, 14 Oct 2025 01:20:05 GMT

My testing in arc pro 3.5 still reproduced the issue of model builder lossing the field mappings.

Re: Merge model builder does not preserve Field Map setting

NevilleWilson_Everick — Tue, 14 Oct 2025 01:23:01 GMT

still a bug in 3.5