I have updated one of my installations from 3.6.5 to 3.7 - beta4 (but the same effect is in beta3 and the newest nightly build).

When I click on the button "install language" in com_install, I get the Error 500-malformed.

It seems to me that during the installation process, the #__update_server is not updated correctly.

In com_installer/models/languages, the query in getUpdateSites() gives an empty result.

The following JHttp request returns the message "malformed" which is then thrown as an exception.