The error Cannot read properties of undefined (reading 'checkValid') is a known issue in Dify Docker deployments and usually means the frontend is trying to validate a workflow node, but the required metadata or validator function is missing or not initialized. This often happens due to a corrupted or invalid DSL YAML file, misconfigured environment variables, or incomplete Docker images. It can also be triggered if the frontend and backend images are mismatched or if static assets are missing or overwritten.

Here's a troubleshooting checklist:

1. Make sure you're using the official Dify web image for version 1.9.1 and not a custom build. Avoid mounting host volumes over the app's static or chunk directories in Docker Compose.
2. Clear your browser cache or try a different browser/device—browser caching has caused similar errors for other users.
3. Rebuild the Docker image from scratch and redeploy:

   docker compose build
   docker compose up -d
   

4. Double-check all environment variables in your .env and docker-compose.yml files, especially any NEXT_PUBLIC_* or domain-related variables. If you upgraded from an earlier version, ensure your .env matches the template for 1.9.1.
5. If the error started after importing or editing a workflow, your DSL YAML file may be corrupted. Try manually cleaning or fixing the YAML (removing problematic nodes) and re-importing it.
6. Make sure both frontend and backend images are the same version.
7. If the issue persists, check Docker logs for both frontend and backend containers for related errors.

Recent versions of Dify have improved validation and error handling for these cases, so consider updating if possible. For more details and similar cases, see this issue and this troubleshooting guide.

To reply, just mention @dosu.

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After upgrading to version 1.10.1, the problem has been solved. Thank you for your guidance