> ## Documentation Index
> Fetch the complete documentation index at: https://docs.ntop.com/llms.txt
> Use this file to discover all available pages before exploring further.

# List Length Error

## Input list length mismatch

### About the error

**Issue:**
When two lists of different lengths are input into a block. The block can't run because it is trying to match the two lists together.

**Applies to:**

* Any block that accepts two or more list inputs
  * Common examples include:
    * Math blocks (ex. Add, Subtract, Divide, Multiply and Pow)
    * Evaluate Field
    * Evaluate Field Gradient

**Cause:**

* Lengths of lists are not equal.
* Unintentional lists of (1) are used with another list input. Open up the input block's properties to check if it is a list type. It will have (#) in the block name.

**Solution:**

* Ensure that the list length of both the operands are the same.
* If you do have an unintentional list of (1), open up the block properties and drag out the chip that has \[0] in the name (typically beneath all other properties). Drag this into the Notebook or directly into another block input.

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