Merge model builder does not preserve Field Map setting

[LucileFayolle]

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

[SarahHartholt]

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.

[PhilipMarty]

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

Any way to escalate it?

[aynow]

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).

[DaveronSmith]

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

[CMorneau]

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?

[AaronLowe]

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.

[Kaksak]

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.

[AaronLowe]

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

[MandP]

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.