Recently several users of the Semi-Automatic Classification Plugin (SCP) for QGIS reported errors that prevented the search and download of Sentinel-2 images.
The issues were caused mainly by the cryptographic protocols used for accessing data and the way the SCP tries to connect to the Copernics Data Hub (https://scihub.copernicus.eu).
In particular, the issues started after some recent changes of the Copernics Data Hub, when the protocols used for accessing data were upgraded (i.e. TLS v1.1+).
The SCP relies on Python for downloading Sentinel-2 images.
As described here https://docs.python.org/2/library/ssl.html the protocols TLS v1.1 and TLS v1.2 are available only in Python 2.7.9+ with openssl version 1.0.1+.
Unfortunately QGIS comes with a previous version of Python where TLS v1.1 and TLS v1.2 are not available. Therefore the Sentinel-2 download process fails.
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