lix/doc/manual/rl-next/source-location-in-while-evaluating-attribute.md

---
synopsis: "In the debugger, `while evaluating the attribute` errors now include position information"
prs: 9915
---

Before:

```
0: while evaluating the attribute 'python311.pythonForBuild.pkgs'
0x600001522598
```

After:

```
0: while evaluating the attribute 'python311.pythonForBuild.pkgs'
/nix/store/hg65h51xnp74ikahns9hyf3py5mlbbqq-source/overrides/default.nix:132:27

   131|
   132|       bootstrappingBase = pkgs.${self.python.pythonAttr}.pythonForBuild.pkgs;
      |                           ^
   133|     in
```