# Ecmwf-opendata source="azure" failing – Planetary Computer SAS token endpoint certificate error

**URL:** <https://forum.ecmwf.int/t/ecmwf-opendata-source-azure-failing-planetary-computer-sas-token-endpoint-certificate-error/15327>\
**Category:** AIFS, IFS and OpenIFS\
**Created:** [15 September 2026 21:48 UTC](https://forum.ecmwf.int/t/ecmwf-opendata-source-azure-failing-planetary-computer-sas-token-endpoint-certificate-error/15327 "2026-09-15T21:48:11Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![Brian\_Gaze](https://forum.ecmwf.int/letter_avatar_proxy/v4/letter/b/4bbf92/32.png) [@Brian\_Gaze](https://forum.ecmwf.int/u/Brian_Gaze)\
**Post date:** [15 September 2026 21:48 UTC](https://forum.ecmwf.int/t/ecmwf-opendata-source-azure-failing-planetary-computer-sas-token-endpoint-certificate-error/15327/1 "2026-09-15T21:48:11Z")

</div>

Since this evening (15 Sept), Client(source=“azure”) fails during initialisation. The SAS token request to

[https://planetarycomputer.microsoft.com/api/sas/v1/token/ai4edataeuwest/ecmwf](https://planetarycomputer.microsoft.com/api/sas/v1/token/ai4edataeuwest/ecmwf)

returns an SSL error:

[SSL: CERTIFICATE\_VERIFY\_FAILED] certificate verify failed: Hostname mismatch, certificate is not valid for ‘[planetarycomputer.microsoft.com](http://planetarycomputer.microsoft.com)’

It reproduces from an Azure VM (Python/requests) and from a home PC browser, so it appears to be a Microsoft-side certificate issue rather than a local one. Switching to source=“aws” works as a workaround.

Thanks

Brian