topic Re: Coordinate system error when attempting to switch to a GeoPDF basemap in an offline map in ArcGIS Field Maps Questions

Coordinate system error when attempting to switch to a GeoPDF basemap in an offline map

BradyCallahan — Tue, 28 Apr 2026 20:48:50 GMT

I'm getting a "Basemap Unavailable - The spatial reference isn't compatible with this map" error when attempting to switch to a GeoPDF basemap in an offline Map.

I created three GeoPDFs in Pro, all at the same time, and side-loaded them to the Basemap folder on my device. They all show up in the Basemap Gallery in Field Maps and work fine in dynamic maps. However, if I attempt to pick one while using an offline map I get that spatial reference error.

I made sure that the Map SRS in Pro was set to WKID:3857 before exporting the GeoPDFs. However, one oddity is that when I brought them back in to Pro, their WKIDs are listed as the outdated Web Mercator tag of WKID:3785.

Anyone else seeing these types of issues or got any ideas?

iOS 26.3.1
Field Maps 26.1.1
ArcPro 3.5

Re: Coordinate system error when attempting to switch to a GeoPDF basemap in an offline map

JonathanLebowitz — Tue, 28 Apr 2026 21:46:38 GMT

Hello. When authoring the map, was the GeoPDF specified on the Offline page of Field Maps Designer or in the item details of the map per Prepare maps for download? Was the original basemap in the map also in PCS WGS 84 Web Mercator/EPGS 3857? How did you bring the GeoPDF back into Pro?

Re: Coordinate system error when attempting to switch to a GeoPDF basemap in an offline map

BradyCallahan — Tue, 28 Apr 2026 22:18:29 GMT

@JonathanLebowitz

I've tried it by pre-specifying a GeoPDF as the offline basemap in the item details page and also without specifying an offline basemap at all (just using the Map default). Results were the same.

Yes, the original basemap in the map was also EPSG:3857, its the World Imagery layer. My GeoPDF's are just exports of three different ESRI basemaps, Pencil, Antique, and Community. No other layers at all.

Brought the GeoPDF back to Pro by a drag-and-drop, then checked it's properties through the TOC.

I've been referring to Jeff Shaner's March 2, 2026 blog post about using GeoPDF's

https://www.esri.com/arcgis-blog/products/field-maps/field-mobility/add-geospatial-pdfs-to-your-field-maps-workflows

Re: Coordinate system error when attempting to switch to a GeoPDF basemap in an offline map

JonathanLebowitz — Tue, 28 Apr 2026 23:26:37 GMT

Thank you for clarifying that. You are likely hitting open bug ID BUG-000183698 in ArcGIS Pro. A summary of the bug is as follows: "When exporting a map layout as an georeferenced PDF in ArcGIS Pro, the geoinformation from layers in the WGS 84 / Pseudo-Mercator (EPSG:3857) coordinate system is incorrectly written to the deprecated Popular Visualisation CRS / Mercator (EPSG:3785) coordinate system." Do you have the ability to open a Technical Support case to get attached to the bug? If not, I can share the public bug status link once it becomes available.

The workaround is to use the Project Raster (Data Management) tool on the PDF file to re-project it from Popular Visualisation CRS Mercator/3785 to WGS 1984 Web Mercator/3857. The geographic transformation should automatically populate as WGS_1984_Major_Auxiliary_Sphere_To_WGS_1984, which is a NULL transformation.

Re: Coordinate system error when attempting to switch to a GeoPDF basemap in an offline map

JonathanLebowitz — Thu, 30 Apr 2026 01:16:32 GMT

Hi Brady. I realized that the workaround documented in the bug may not be valid for your use case as the Project Raster tool does not support the .pdf file extension for the "Output Raster Dataset," and you are trying to sideload the basemaps onto your devices. Unfortunately, you may need to wait for the bug to get fixed. You can provide additional information about the business impact of the bug in My Esri by following the steps at https://support.esri.com/en-us/knowledge-base/provide-a-business-impact-statement-for-a-bug-000024129 or by contacting your Accounts Team.

Re: Coordinate system error when attempting to switch to a GeoPDF basemap in an offline map

BradyCallahan — Thu, 30 Apr 2026 14:30:45 GMT

I opened a support ticket and they got back to me with this same information early this morning. I guess this got rolled out a bit prematurely. Bummer.

Re: Coordinate system error when attempting to switch to a GeoPDF basemap in an offline map

BradyCallahan — Thu, 30 Apr 2026 18:32:53 GMT

Hmmm... I found that I can update the CRS in a GeoPDF using GDAL in Pro

from osgeo import gdal gdal.Translate('GeoPDF_out.pdf', 'GeoPDF_in.pdf', format="PDF", outputSRS="EPSG:3857")

When I review the output GeoPDF file CRS properties in Pro all looks great and it draws in the correct location in a Map. However, when I bring it into Field Maps I get a slightly different error than before "Basemap Unavailable - The basemap doesn't have a valid spatial reference"

This is odd since it is working correctly in Pro.

Re: Coordinate system error when attempting to switch to a GeoPDF basemap in an offline map

JonathanLebowitz — Thu, 30 Apr 2026 19:27:00 GMT

Interesting. I wonder if the gdal.Translate() method is somehow stripping the PDF of the geospatial information that Field Maps needs. Is there another format you can specify for "geospatial PDF?"

Re: Coordinate system error when attempting to switch to a GeoPDF basemap in an offline map

BradyCallahan — Thu, 30 Apr 2026 19:35:06 GMT

I don't know but I just tried bypassing Pro entirely by exporting a GeoPDF using the print widget in an AGOL webmap. I was thinking I'd get a clean file that way. The output draws fine in Pro, CRS looks good. Does Field Maps like it? Nope.

Its starting to seem to me that there's more here than just a BUG with Pro.

Re: Coordinate system error when attempting to switch to a GeoPDF basemap in an offline map

JonathanLebowitz — Thu, 30 Apr 2026 19:57:31 GMT

Is the behavior any different if you browse for the PDF item in your organization instead of sideloading it?

Re: Coordinate system error when attempting to switch to a GeoPDF basemap in an offline map

BradyCallahan — Thu, 30 Apr 2026 23:26:20 GMT

Not exaclty sure what you mean about browsing for the item in my org.

If I upload the PDF to AGOL and make it available to Field Maps there doesn't appear to be a way to have that PDF available as a basemap on the device unless I lock a Web map to it. I can do that however, and when I go offline, the PDF gets downloaded as the basemap. The issue though is that there's no way to change the basemap to a different PDF without running into the error.

Just got the notice below

BUG-000183698 has been closed: As Designed.
This is as designed, it is a workaround related to the limitations of Adobe products. The Esri Projection Engine included in Adobe Acrobat is an older version that does not support Web Mercator (EPSG 3857). In order to provide any georeference information in exported PDFs using Web Mercator, we write an older EPSG code that is properly supported by the projection engine version included in Adobe products. If at some future juncture Adobe updates their copy of the projection engine, we could modify PDF export to write the newer Web Mercator Auxiliary Sphere.

Re: Coordinate system error when attempting to switch to a GeoPDF basemap in an offline map

JonathanLebowitz — Fri, 01 May 2026 00:02:58 GMT

I guess my question was essentially if you were able to download it from ArcGIS Online and open it up in Field Maps without an error message. I will need to investigate if the Field Maps team is aware of this limitation since Esri basemaps are defined in WGS 84 Web Mercator.

Re: Coordinate system error when attempting to switch to a GeoPDF basemap in an offline map

BradyCallahan — Thu, 07 May 2026 21:29:48 GMT

Defect #: ENH-000184814

Synopsis: Enable native support for EPSG:3785 georeferenced PDFs in ArcGIS Field Maps to ensure basemap compatibility with ArcGIS Pro layout exports