topic Re: Basemap does not have a valid spatial reference in ArcGIS Field Maps Questions

Basemap does not have a valid spatial reference

PHATHEKATENGIMFENE — Thu, 26 Feb 2026 07:37:48 GMT

In ArcGIS Field Maps 24.1.3, I am unable to switch the basemap, despite both the map and basemap sharing the same spatial reference. When attempting to switch, I receive the following error message:
"The basemap does not have a valid spatial reference."

Re: Basemap does not have a valid spatial reference

JavierML — Fri, 27 Feb 2026 10:12:24 GMT

Hi @PHATHEKATENGIMFENE,

can you share more information about the case? Is the basemap a custom one or a default one? What Coordinate System do the layers have?

Re: Basemap does not have a valid spatial reference

PHATHEKATENGIMFENE — Fri, 27 Feb 2026 10:51:51 GMT

@JavierML The basemap is a custom basemap and the layers are using WGS_1984_Transverse_Mercator.

Re: Basemap does not have a valid spatial reference

JavierML — Mon, 02 Mar 2026 13:39:46 GMT

Hi @PHATHEKATENGIMFENE ,

sorry for not answering on the weekend.

I see something strange in your screenshots. Your projected coordinate system looks as if it was "Custom". Normally, the projected coordinated system has a defined name, ID and Authority (normally EPSG). Yours doesn't.

It isn't my area of expertise, but I would guess that, after an update or transfering the layer too many times, the Coordinated System is not correctly recognised anymore. Could you try the following:

Use the project tool to create a new layer with a valid Coordinated Sytem (you could try EPSG:3395, EPSG:4326, EPSG:4258,EPSG:3857 or even the 4148 you currently have)
(WGS 1984 World Mercator) and then upload the layers to Field Maps. You can even try and converting it once again into
If you can't reproject, use the tool Define Projection to set the Coordinating System to EPSG:4148 and then try to upload it.

Tell me if it worked or not at the end

Re: Basemap does not have a valid spatial reference

JonathanLebowitz — Thu, 26 Mar 2026 17:01:06 GMT

Hello. ArcGIS Field Maps will not recognize a coordinate system that is missing a WKID (i.e., authority is set to custom).