You can follow below

• Absolute Path - Ensure the path is absolute if you are using Databricks notebook run (/Workspace/Files/Notebook). Don't rely on relative paths. Avoid dynamically constructed paths that may add additional characters triggering Invalid Request URL error.
• Cluster state - Long running clusters sometimes cache invalid routing info. Restart the cluster & try it again.

• Code Practices - Replace chained notebook calls with modular functions & use serverless workflows instead of nested notebook execution.