# Requested color-by field 'num\_date' does not exist

**URL:** <https://nextstrain.discourse.group/t/requested-color-by-field-num-date-does-not-exist/1997>\
**Category:** Help and Getting Started\
**Created:** [September 24, 2025, 7:05pm UTC](https://nextstrain.discourse.group/t/requested-color-by-field-num-date-does-not-exist/1997 "2025-09-24T19:05:20Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![eam](https://avatars.discourse-cdn.com/v4/letter/e/94ad74/32.png) [@eam](https://nextstrain.discourse.group/u/eam)\
**Post date:** [September 24, 2025, 7:05pm UTC](https://nextstrain.discourse.group/t/requested-color-by-field-num-date-does-not-exist/1997/1 "2025-09-24T19:05:20Z")

</div>

Hello! I am loving Nextstrain and currently attempting to create pathogen repositories for two poultry-related viruses. For one of the viruses, I was able to successfully run the default [pathogen-repo-guide](https://github.com/nextstrain/pathogen-repo-guide) ingest workflow and I’m now trying to create a phylogenetic workflow (created from the [pathogen-repo-guide repository](https://github.com/nextstrain/pathogen-repo-guide) template and modified using the measles repo to allow for analysis of just one gene). The workflow successfully runs, but during `augur export v2` I get the warning message `WARNING: Requested color-by field 'num_date' does not exist and will not be used as a coloring or exported.` When I look at the created JSON file on [https://auspice.us/](https://auspice.us/), ‘Sampling date’ is not an option to “Color By” or “Filter Data”. I’m sure this is something _very_ basic, but I’m completely stumped. The ingest workflow creates an output metadata file with the column ‘date’, but neither ‘date’ or ‘num\_date"‘ seem to work in the `auspice_config.json` file:

```auto
  {
    "key": "num_date",
    "title": "Date",
    "type": "continuous"
  },

```

Any help would be greatly appreciated. Thanks so much!

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**Author:** ![joverlee](https://avatars.discourse-cdn.com/v4/letter/j/e495f1/32.png) [@joverlee](https://nextstrain.discourse.group/u/joverlee)\
**Post date:** [September 25, 2025, 12:10am UTC](https://nextstrain.discourse.group/t/requested-color-by-field-num-date-does-not-exist/1997/2 "2025-09-25T00:10:43Z")

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Hi @eam,

In your phylogenetic workflow, are you running `augur refine` to produce a time tree?

Usually, `augur refine` produces an output `branch_lengths.json` that includes the `numdate` attribute for each node. Then, the `branch_lengths.json` is passed as an input to `augur export v2` where `numdate` is renamed to `num_date` to be used for the time tree display in Auspice.

If you are not producing a time tree, then I’d just remove the `num_date` coloring from your `auspice_config.json`.

-Jover

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<div class="post-metadata">

**Author:** ![eam](https://avatars.discourse-cdn.com/v4/letter/e/94ad74/32.png) [@eam](https://nextstrain.discourse.group/u/eam)\
**Post date:** [September 25, 2025, 3:11pm UTC](https://nextstrain.discourse.group/t/requested-color-by-field-num-date-does-not-exist/1997/3 "2025-09-25T15:11:57Z")

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Wow, I feel silly. I was running `augur refine`, but somehow deleted the `--timetree` flag. I do get dates now. I did notice that when no sampling date was provided (i.e. `XX-XX-XXXX`), the date in auspice is `1`. The reference date is also listed as `-77`. Is this to be expected?

Thank you so much for your continued help!

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<div class="post-metadata">

**Author:** ![joverlee](https://avatars.discourse-cdn.com/v4/letter/j/e495f1/32.png) [@joverlee](https://nextstrain.discourse.group/u/joverlee)\
**Post date:** [September 25, 2025, 6:50pm UTC](https://nextstrain.discourse.group/t/requested-color-by-field-num-date-does-not-exist/1997/4 "2025-09-25T18:50:32Z")

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`augur refine` infers the most likely date for nodes with ambiguous dates using [TreeTime](https://github.com/neherlab/treetime), which outputs negative values to indicate BCE years. If you know these inferred dates are too early, you can specify boundaries for the year with the `--year-bounds` option. For example, if you analysis only includes data from 2020 and after, you can add `--year-bounds 2020`. If your data is from 2020 to 2024, you can add `--year-bounds 2020 2024`.