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

# Errors

> Overview of common errors and their explanations.

<AccordionGroup>
  <Accordion title="#DIV/0">
    The `#DIV/0` error occurs when an attempt is made to divide a value by zero (0). Division by zero is mathematically undefined and therefore not permitted.

    <Info>
      To prevent future occurrences of the `#DIV/0` error, use the `IGNORE_DIV_ZERO()` function. Learn more [here](/documentation/features/modeling/functions).
    </Info>
  </Accordion>

  <Accordion title="#NO_FRAC">
    The `#NO_FRAC` error arises when a row is aggregated using a weighted average (W\.AVG), but the formula for the row contains something other than a simple fraction (`a/b`)
  </Accordion>

  <Accordion title="#ERR">
    The `#ERR` error typically indicates an issue with invalid syntax or an incomplete formula. For instance, entering `5+` in the formula editor results in `#ERR` because the plus sign (+) is incomplete and requires an additional value.
  </Accordion>

  <Accordion title="#INF_LOOP">
    The `#INF_LOOP` error is triggered when an infinite loop is detected, typically caused by a recursive back-reference. This often happens when a calculation references itself. Since calculations are consistent across all periods (the same formula applies in each period), self-referencing leads to an infinite loop, which is not supported.
  </Accordion>

  <Accordion title="#CIRCULAR">
    The `#CIRCULAR` error is caused by defining a circular dependency between cells. For example, this might occur when two cells, `a` and `b`, reference each other, or when a series of cells collectively create a circular dependency.
  </Accordion>

  <Accordion title="#FUTURE_REF">
    The `#FUTURE_REF` error happens when references are made to future periods. Francis only supports references to cells in the current period or earlier.

    <Info>
      If the index in your cell reference is greater than `0`, a `#FUTURE_REF` error will always be thrown. For example, `Revenue[1]` is invalid because it refers to the `Revenue` row one month into the future. However, `Revenue[0]` and `Revenue[-1]` are valid references, as they point to the current and prior months, respectively.
    </Info>
  </Accordion>

  <Accordion title="#INVALID_REF">
    The `#INVALID_REF` error typically occurs when a reference is made to a cell that does not exist. This is often the result of referencing a row that was deleted.
  </Accordion>

  <Accordion title="#BAD_ARG">
    The `#BAD_ARG` error occurs when an argument provided to a function does not match the expected input type. This may include using a boolean value where a number is expected, or vice versa.

    <Info>
      To avoid the `#BAD_ARG` error, carefully review the Docs on [functions](/documentation/features/modeling/functions) to ensure you are using the correct input types while building your model.
    </Info>
  </Accordion>

  <Accordion title="#BAD_TYPE">
    The `#BAD_TYPE` error occurs when an argument provided to a function is of an incompatible type. For example, supplying a number or boolean when the function expects a range.
  </Accordion>

  <Accordion title="#REF_ERR">
    The `#REF_ERR` error is returned when a cell references another cell that contains an error. Essentially, if your formula points to a cell with any of the errors mentioned above, Francis will return a `#REF_ERR`.
  </Accordion>
</AccordionGroup>