How can I fix it?

I use the transport of diluted species to solve a porous media problem but water contain steady inside without diffuse and the result shown in following error. What should I do?
Undefined variable.
- Variable: comp1.v
- Geometry: geom1
- Domain: 6
Failed to evaluate operator Jacobian.
- Operator: mean
- Geometry: geom1
- Boundary: 20
Failed to evaluate variable Jacobian.
- Variable: comp1.tds.v
- Geometry: geom1
- Boundary: 20