topic WebMap object getting TraitError from webmapitem in ArcGIS API for Python Questions

WebMap object getting TraitError from webmapitem

AnthonyRyanEQL — Tue, 09 Nov 2021 07:34:09 GMT

Hi all,

I'm using the example from the ArcGIS Python API doco on how to search for portal items, filter by Web Map. From here I want to get the list of layers within this map but I'm getting an TraitError

wm_item = gis.content.get('6229f30bb378405397b24615e8dcaf60')

wm = WebMap(wm_item)

TraitError: The 'comm' trait of a Layout instance must be a Comm or None, but a value of class 'ipykernel.comm.comm.Comm' (i.e. <ipykernel.comm.comm.Comm object at 0x000002630B46DE48>) was specified.

Currently using the python within ArcGIS Pro 2.7 with Patch 4 applied.

Has anybody come across this/know what I'm doing wrong?

Thanks

Re: WebMap object getting TraitError from webmapitem

ABishop — Tue, 09 Nov 2021 18:46:42 GMT

Hello Anthony,

Where are you running this script from?

Re: WebMap object getting TraitError from webmapitem

JeffreyBurka — Mon, 17 Oct 2022 13:35:12 GMT

(old question, but I just ran into the same thing and found this, so I'm adding what worked for me so google will crawl it!)

As far as I could tell, this was basically just a problem the jupyter kernel being unhappy in Pro. Quitting and relaunching Pro cured the issue for me.

A little more detail on my situation: I wrote a python script and got it working the way I wanted, then used that as the basis for a Python Toolbox (.pyt). When running the tool created from the script, I was getting the "The 'comm' trait of a Layout instance expected a Comm or None trait" error while creating a WebMap from a web map item already retrieved from the portal. The standalone script continued to work; only the GP tool was failing in this way. Quitting and relaunching Pro cleared it up.

Re: WebMap object getting TraitError from webmapitem

Chris_Kell — Wed, 20 Sep 2023 15:59:13 GMT

I found this post via Google, and restarting pro worked for me. Thanks for the tip!

Re: WebMap object getting TraitError from webmapitem

CSDING_GIS — Mon, 08 Sep 2025 12:34:56 GMT

I'm running into the same error, except the error statement reads a little bit different now:

traitlets.traitlets.TraitError: The 'comm' trait of a Layout instance expected a Comm or None, not the Comm at '0x1ef84ef3d90'.

I'm getting this error in a jupyter notebook, but also in the direct python window.

I'm on Pro v3.3.1 wirh Python v3.11.8