Unable to open any of the demos (error CS0582: Attribute 'SerializeField' is not valid on this declaration type. It is only valid on 'field' declarations.)

[MOSMekawy]

I tried multiple unity editor versions but none of them work. Some crash and some just throw error.
My latest attempt was using this config/environment.

Environment:

• Windows 11
• Unity 6.4 (6000.4.0f1)
• SofaUnity-URP_v25.12_public_2025-03-20

Error:

• error CS0582: Attribute 'SerializeField' is not valid on this declaration type. It is only valid on 'field' declarations

Warnings:

• The GUID inside 'Assets/SofaUnity/Core.meta' cannot be extracted by the YAML Parser. Attempting to extract it via string matching instead. Please verify the file does not contain unexpected data.
• ImportFBX Warnings: Can't import normals, because mesh 'default' doesn't have any.
• Mesh 'default' has no normals. Recalculating normals.

[epernod]

Hi @MOSMekawy ,

I converted your issue into a github discussion.
could you describe exactly the behavior. When you create a blank project and then import the package, it crashes directly?
Or did the package was fully loaded and as soon as you try to run a scene it crashes?

Could you send the full Player.log file?

Best regards

[MOSMekawy]

No, It was fully loaded and upon adding any of the demo scenes and running them, I am prompted to fix compilation error first and the error I shared shows up in the console.

Unfortunately I am unable to locate the Player.log file. Can you provide instructions as to how to locate it ?

[MOSMekawy]

Hi @epernod,
Do you have any insight into this issue ? I've tried multiple versions of unity and the sofa unity plugin and the issue stilll remains.