Please review in relation to making changes to the scripts and the error!
Help | Structural Analytical Model Automation Guide | Autodesk
If no changes have been made then this usually happens because the Dynamo scripts are not in the default locations on your PC.
The workaround is to copy the whole Dynamo folder from the location where its installed by default (C:\ProgramData\Autodesk\RVT 2026) to the location where you choose to install the content, next to the "Family Templates" folder.
The exact location where you should copy the folder is recorded in Revit\File\Options\File Locations\Default Path for family templates files:

This thread is useful to compare your installation setup which I have used previously for similar issues.
Revit 2026 Analytical Automation Error - Autodesk Community
Jay Colcombe
Autodesk Certified Instructor
Revit Architecture & Structure Certified Professional
AutoCAD Certified Professional
B.Sc. Hons Civil & Structural Engineering
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