# \[rebuild\_nemo\] Fails with "NetCDF: Attribute not found" on grid\_W files

**URL:** https://nemo-ocean.discourse.group/t/rebuild-nemo-fails-with-netcdf-attribute-not-found-on-grid-w-files/886
**Category:** v4.0.x
**Created:** [24 April 2025 06:44 UTC](https://nemo-ocean.discourse.group/t/rebuild-nemo-fails-with-netcdf-attribute-not-found-on-grid-w-files/886 "2025-04-24T06:44:46Z")
**Posts on this page:** 2
**Page:** 1

<div class="post-metadata">

### Author: ![cjdrornfl110](https://avatars.discourse-cdn.com/v4/letter/c/a587f6/32.png) [@cjdrornfl110](https://nemo-ocean.discourse.group/u/cjdrornfl110)
#### Post date: [24 April 2025 06:44 UTC](https://nemo-ocean.discourse.group/t/rebuild-nemo-fails-with-netcdf-attribute-not-found-on-grid-w-files/886/1 "2025-04-24T06:44:46Z")

</div>

I’m quite new to using NEMO and still trying to understand how the model output and tools like `rebuild_nemo` work. Please excuse me if I’ve misunderstood anything basic.

I’m using NEMO version 4.0.1 and trying to rebuild domain-decomposed `grid_W` output files using `rebuild_nemo`.

- Files: ORCA2\_1m\_20010101\_20011231\_grid\_W\_0000.nc … ORCA2\_1m\_20010101\_20011231\_grid\_W\_0035.nc (36 domain-decomposed files)
- `nam_rebuild` used:

```auto
&nam_rebuild
filebase='ORCA2_1m_20010101_20011231_grid_W'
ndomain=36
l_maskout=.false.
nslicesize=0
deflate_level=1
nc4_xchunk=206
nc4_ychunk=135
nc4_zchunk=1
nc4_tchunk=1
fchunksize=32000000

```

- Command:

```auto
bash
./rebuild_nemo.exe

```

ERROR! : NetCDF: Attribute not found  
\*\*\* NEMO rebuild failed \*\*\*

I’m wondering if the merging issue I’m facing might be related to unexpected metadata or variables present in the domain-decomposed files. Specifically, even though I’m rebuilding the `grid_W` files, the original domain-decomposed files contain global attributes or metadata related to `grid_T` (for example, attributes such as `ibegin_grid_T`, `nj_grid_T`, etc.).

Could the presence of these grid-specific attributes confuse `rebuild_nemo` during the merging process?

Should these attributes or variables be manually removed from the files before running `rebuild_nemo`?

However, even when I used `cdo` to explicitly remove the `grid_T` related variables and metadata before running `rebuild_nemo`, the merge still failed.

---

<div class="post-metadata">

### Author: ![smasson](https://avatars.discourse-cdn.com/v4/letter/s/eb9ed0/32.png) [@smasson](https://nemo-ocean.discourse.group/u/smasson)
#### Post date: [28 April 2025 15:00 UTC](https://nemo-ocean.discourse.group/t/rebuild-nemo-fails-with-netcdf-attribute-not-found-on-grid-w-files/886/2 "2025-04-28T15:00:34Z")

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can you send the result of  
`ncdump -h ORCA2_1m_20010101_20011231_grid_W_0000.nc`