topic Re: Field Maps Layer Fails to Load - Error Code 21: Invalid JSON in ArcGIS Field Maps Questions

Field Maps Layer Fails to Load - Error Code 21: Invalid JSON

NickAddison — Mon, 05 Feb 2024 14:56:55 GMT

Uploaded a map to Field Maps and all the other layers load except one; the following error is given:

Domain: com.esri.arcgis.runtime.error

Code: 21

Description: Invalid JSON

The only thing I can think of that is noticeably different about this layer is that it has a litany of attribute rules tied to it and several field types that not accepted by Field Maps (Date Only).

Any thoughts on how to address Error Code 21?

Thanks for any help,

Nick

Re: Field Maps Layer Fails to Load - Error Code 21: Invalid JSON

JoabelBarbieri — Wed, 07 Feb 2024 22:20:39 GMT

Same here

Re: Field Maps Layer Fails to Load - Error Code 21: Invalid JSON

TaylorBlose7 — Fri, 09 Feb 2024 17:55:04 GMT

I'm encountering the same issue with a feature layer and views off that particular layer.

Re: Field Maps Layer Fails to Load - Error Code 21: Invalid JSON

Sietse_de_Haan — Mon, 19 Feb 2024 13:26:30 GMT

I had the same problem today, Error 21. I removed the DateOnly field and created a new field with the formate Date. This fixed my problem.

I also had a warning when creating my form that there was a field that wasnt supported in FieldMaps (DateOnly field).

Hope this helps

Re: Field Maps Layer Fails to Load - Error Code 21: Invalid JSON

KenBragg — Wed, 01 May 2024 07:20:56 GMT

Good answer which helped me, thanks a lot. Also seem that TimeOnly is not supported

Re: Field Maps Layer Fails to Load - Error Code 21: Invalid JSON

NateHollenbeck — Tue, 03 Dec 2024 20:33:27 GMT

Technical support document from the error you are getting: Error: ArcGIS Field Maps Domain: com.esri.arcgis.runtime.error Code 21. Invalid JSON

Also, I found documentation on what field types are not supported in some clients: 24170: <value> contains a field type that may not be fully supported in some clients—ArcGIS Pro | Documentation

I hope this is helpful!

Re: Field Maps Layer Fails to Load - Error Code 21: Invalid JSON

LORAMAdmin — Fri, 24 Jan 2025 16:07:05 GMT

Thank you. This was the reason for my error as well. Changed from DateOnly to Date and all is well.

Re: Field Maps Layer Fails to Load - Error Code 21: Invalid JSON

DougBrowning — Wed, 15 Apr 2026 20:42:13 GMT

I am getting this error but I doubled checked and I do not have any special fields at all. Never used them.

What else could it be? I got about 300 fields per layer but thats not that many.