> For the complete documentation index, see [llms.txt](https://docs.tryterra.co/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.tryterra.co/faq/help-topics/data-api-sdk/historical-data-and-backfill.md).

# Historical data and backfill

Common questions about historical data and backfill.

## Articles

{% content-ref url="/pages/BIR3pxVRJ7qSC7TdPkyR" %}
[Why does Apple Health backfill return empty arrays?](/faq/help-topics/data-api-sdk/historical-data-and-backfill/apple-health-sdk-backfill.md)
{% endcontent-ref %}

{% content-ref url="/pages/tw6hglbQm0LV2isaKnyw" %}
[Why does a historical fetch return a 504 timeout?](/faq/help-topics/data-api-sdk/historical-data-and-backfill/historical-fetch-size-timeouts-504-413-500.md)
{% endcontent-ref %}

{% content-ref url="/pages/N7ZAzPqwpMOMvKrv6dr9" %}
[Why am I hitting rate limits during a backfill?](/faq/help-topics/data-api-sdk/historical-data-and-backfill/provider-rate-limits-backfill.md)
{% endcontent-ref %}

{% content-ref url="/pages/Usq1qUxJd8GAXFMSv6oj" %}
[When is historical data available after connect?](/faq/help-topics/data-api-sdk/historical-data-and-backfill/mobile-native-no-backfill-sdk-fetch.md)
{% endcontent-ref %}

{% content-ref url="/pages/YqAVCfGBHe2E7aLCsdNT" %}
[Can the SDK retrieve historical data, and over what period?](/faq/help-topics/data-api-sdk/historical-data-and-backfill/sdk-backfill-historical-retrieval.md)
{% endcontent-ref %}

{% content-ref url="/pages/VN65prEKWiknZ9AOGHJh" %}
[Why did old Garmin payloads arrive without my request?](/faq/help-topics/data-api-sdk/historical-data-and-backfill/garmin-unrequested-historical-payloads.md)
{% endcontent-ref %}

{% content-ref url="/pages/Ab4eRUCaa7pJxabw2DpX" %}
[How do CGM glucose webhook payloads work?](/faq/help-topics/data-api-sdk/historical-data-and-backfill/cgm-glucose-body-payload-delivery-history.md)
{% endcontent-ref %}

{% content-ref url="/pages/PwOahtJFV6QRFEyekp0n" %}
[Can I default Garmin historical data permission on?](/faq/help-topics/data-api-sdk/historical-data-and-backfill/garmin-historical-data-permission-off-default.md)
{% endcontent-ref %}

{% content-ref url="/pages/k39eEIMA0QsGuuNjB6TO" %}
[Why is a workout timestamp weeks in the past?](/faq/help-topics/data-api-sdk/historical-data-and-backfill/apple-late-historical-workout-timestamps.md)
{% endcontent-ref %}

{% content-ref url="/pages/WMVUeCQFTI6CxViUU8PU" %}
[Can I see the COROS historical-consent choice?](/faq/help-topics/data-api-sdk/historical-data-and-backfill/coros-historical-consent-not-surfaced.md)
{% endcontent-ref %}

{% content-ref url="/pages/3zqd7XoXjJB6K8HbNGRe" %}
[Are there limits on Wahoo backfill requests?](/faq/help-topics/data-api-sdk/historical-data-and-backfill/wahoo-backfill-no-rate-limit.md)
{% endcontent-ref %}

{% content-ref url="/pages/IG3sf0CJu6Tkgp6uW4bK" %}
[How do I detect backfill completion with S3 destinations?](/faq/help-topics/data-api-sdk/historical-data-and-backfill/s3-reference-id-and-backfill-completion.md)
{% endcontent-ref %}

{% content-ref url="/pages/gnBEFCfDNUPsnOZ95yBY" %}
[Why isn't the backfill / Sync Now button working?](/faq/help-topics/data-api-sdk/historical-data-and-backfill/historical-date-param-format.md)
{% endcontent-ref %}