MB003: cycle-dependencies

🚨 Breaking ❌ Not Fixable

MB003: Cells have circular dependencies.

What it does

Analyzes the dependency graph to detect circular references between cells, where cells depend on each other in a way that creates an impossible execution order.

Why is this bad?

Circular dependencies prevent marimo from: - Determining a valid execution order - Running notebooks reproducibly - Executing notebooks as scripts - Providing reliable reactive updates

This is a breaking error because it makes the notebook non-executable.

Examples

Problematic:

# Cell 1
a = b + 1  # Reads b

# Cell 2
b = a + 1  # Reads a -> Cycle!

Solution:

# Cell 1
a = 1

# Cell 2
b = a + 1  # Unidirectional dependency

References

• Cycles Guide
• Understanding Errors