Json exception since upgrade from 2.1.3 to 3.0.2

[JuEocene]

Hello,

A few days ago, we upgraded Umbraco from version 10 to 13. As part of this, we also updated Umbraco GMaps. Since then, we've encountered some issues.

When trying to access a page that uses a doctype with a GMaps property, we receive the following error:
JsonException: The JSON value could not be converted to System.Nullable`1[Our.Umbraco.GMaps.Models.MapType].

I have attempted several fixes, including:

Removing the custom map style JSON.
Changing the map type from "styled map" to "roadmap," "hybrid," "satellite," and "terrain."
Unfortunately, none of these worked, and they also made the application unstable. I encounter the following error:

ModelBindingException: Cannot bind source content type Umbraco.Cms.Web.Common.PublishedModels.Homepage to model type Umbraco.Cms.Web.Common.PublishedModels.Master. Both view and content models are in-memory generated, with different versions. The application is in an unstable state and should be restarted.

This forces me to restart the application to recover.

Would you have any insight into what might be causing these issues, or potential solutions?

Thank you for your help!

[imZEH]

I'm getting similar issue. by any chance , Have you found any fixes for this ?

[imZEH]

I have done several troubleshooting and got me into attaching the package source code and from there found out that the old JSON data we have from upgrading Umbraco version doesn't correctly parse the JSON data. From there you can modify the source code to parse the JSON that suites your needs.

[JuEocene]

Hi,
No, I haven't found a way to fix it yet.
I just downgraded the GMaps version to 2.1.3, and fortunately, it works with Umbraco 13.
Thanks for your suggestion for the fix. I'll try it asap.