Allplan Forum: Object reference not set to an instance of an object.

uid-473994

18.12.2025 - 15:54

Hello everyone,

I am continuously getting an error when I try to place rebars using Visual Scripting. I also checked the Allplan help files (LBar.avsprj)), but the problem is the same.

Whenever I change a value (for example Biegerollendurchmesser), I keep receiving the same error message:
“Failed to update value from palette: Object reference not set to an instance of an object.”
In addition, I do not see any changes in the rebar detailing after modifying the parameters. It looks like the script does not react to the updated values at all.

Has anyone experienced something similar or knows how to solve this issue?
Any suggestions or guidance would be greatly appreciated.

Thank you!

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xinling

07.01.2026 - 12:12

Which ALLPLAN version are you using? Can you provide the avsprj file and the instruction about how to use that? So that we can try to reproduce it?
If you found out our examples also have the same issue, you can also mentioned it. That will help us to identify the issue.

Product Owner API, Allplan GmbH

uid-473994

07.01.2026 - 12:20

Since I am new to Allplan and visual programming, I didn’t fully understand how the whole workflow with the Python parts works. That was the issue. Once I created the objects, I understood how the workflow works, and now I no longer get this error. The error occurred because I was making changes to the objects before they were created.