I have this same error. But mine arose because the installed theme did not appear in the list of themes when it was not in use. Its folder was in ~/.themes, but it didn't show up in "appearance preferences". I deleted the ~/.themes folder and reinstalled. It still didn't show up, but could be used until I rechanged the theme.
I have this same error. But mine arose because the installed theme did not appear in the list of themes when it was not in use. Its folder was in ~/.themes, but it didn't show up in "appearance preferences". I deleted the ~/.themes folder and reinstalled. It still didn't show up, but could be used until I rechanged the theme.