Basemap does not have a valid spatial reference

[PHATHEKATENGIMFENE]

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."

[JavierML]

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?

[PHATHEKATENGIMFENE]

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

[JavierML]

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

[JonathanLebowitz]

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