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.
A temporary solution for Windows OS:
Warning: this could break other QGIS functions, but fortunately you can install multiple versions of QGIS
- Download and install Python for 32bit from here or for 64bit from here according to the installed version of QGIS
- Copy and replace C:\python27\python.exe to "QGIS installation folder"\bin\
- Copy and replace C:\python27\pythonw.exe to "QGIS installation folder"\bin\
- Copy and replace all the content of C:\python27\ to "QGIS installation folder"\apps\python27\
- Now start QGIS and if everything went well you should be able to search and download Sentinel-2 images using SCP
In the meantime you can install an older version of QGIS (e.g. 2.8.3) from http://qgis.org/downloads/QGIS-OSGeo4W-2.8.3-1-Setup-x86.exe should work or the 64bit version from http://qgis.org/downloads .
For other Operating Systems such a Linux, if you had this issue you should be able to upgrade the installed Python version directly. For Mac users, you can try the Semi-Automatic OS virtual machine.
Hopefully, a more recent version of Python will be included in the future versions of QGIS for Windows and this workaround won't be required.
Thank you very much to all the users the reported the errors and helped me to find the solution to this issue.