My problem was resolved by manual reinstallation. I had to first manually delete the wp-contect/plugins/device-theme-switcher folder as reinstallation did not work without this step. The folders structure remained existing in the wp files tree structure after previous try to update DTS to version 2.7 automatically. This process failed for to me unknown reason and deleted plugin from wp plugin tab. The files of pluging remained on disk and blocked new manual reinstallation. Therefore the steps named above were necessary before new manual installation. After manual reinstallation, the setup of DTS appeared to be OK as previously. It was probably pulled from DB, which was not touched during all above named steps….
