Upgrading to 1.3 with error?

[mash55]

• running weewx 4.10.2 on a raspberry pi
• trying to upgrade from belchertown 1.2 to the latest 1.4
• sudo wee_extension --install ./weewx-belchertown-release-1.3.tar.gz generates
  Request to install './weewx-belchertown-release-1.3.tar.gz' Extracting from tar archive ./weewx-belchertown-release-1.3.tar.gz Traceback (most recent call last): File "/usr/share/weewx/wee_extension", line 92, in <module> main() File "/usr/share/weewx/wee_extension", line 84, in main ext.install_extension(options.install) File "/usr/share/weewx/weecfg/extension.py", line 130, in install_extension self.install_from_dir(extension_dir) File "/usr/share/weewx/weecfg/extension.py", line 220, in install_from_dir save_config |= self._inject_config(installer['config'], extension_name) File "/usr/share/weewx/weecfg/extension.py", line 259, in _inject_config weecfg.prepend_path(cfg, 'HTML_ROOT', self.config_dict['StdReport']['HTML_ROOT']) File "/usr/lib/python2.7/dist-packages/configobj.py", line 554, in __getitem__ val = dict.__getitem__(self, key) KeyError: 'HTML_ROOT'
• sudo wee_extension --list tells me version 1.2 is still installed
• $belchertown_version (in the about.inc) tells me 1.3 is running

Do I have to uninstall version 1.2 first?
Any input highly appreciated.