> For the complete documentation index, see [llms.txt](https://docs.aurelia.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.aurelia.io/developer-guides/error-messages/0001-to-0023/aur0020.md).

# AUR0020

No defined value found when calling firstDefined()

### **Error message**

No defined value found when calling firstDefined()

### **Parameters**

None

### Error explanation

This error occurs when the `firstDefined()` utility function is called with a list of values, but none of the values are defined (i.e., all are `undefined`). The function is intended to return the first non-undefined value, and throws this error if none is found.

### Common causes

* All arguments passed to `firstDefined()` are `undefined`.
* There is a logic error in the code that generates the values for `firstDefined()`.
* The function is used in a context where at least one value should always be defined, but none are.

### How to fix

* Ensure that at least one argument passed to `firstDefined()` is defined (not `undefined`).
* Check the logic that produces the values for `firstDefined()` to ensure it is working as expected.
* Add appropriate fallbacks or default values if necessary.

### Debugging tips

* Check the stack trace to see where `firstDefined()` was called.
* Inspect the values being passed to `firstDefined()` at the point of the error.
* Add logging or breakpoints to verify the expected values are present.


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