Roscore fails to start

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Hi, I am having a problem when I am trying to start roscore on the terminal; i get the following error: By the way, I am using the melodic distro on its latest update. THANKS!

WARNING: unable to configure logging. No log files will be generated
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Traceback (most recent call last):
  File "/usr/bin/rosversion", line 11, in <module>
    load_entry_point('rospkg==1.1.10', 'console_scripts', 'rosversion')()
  File "/usr/lib/python2.7/dist-packages/rospkg/rosversion.py", line 104, in main
    version = rosstack.get_stack_version(args.package)
  File "/usr/lib/python2.7/dist-packages/rospkg/rospack.py", line 422, in get_stack_version
    return get_stack_version_by_dir(self.get_path(stack))
  File "/usr/lib/python2.7/dist-packages/rospkg/rospack.py", line 201, in get_path
    self._update_location_cache()
  File "/usr/lib/python2.7/dist-packages/rospkg/rospack.py", line 184, in _update_location_cache
    list_by_path(self._manifest_name, path, cache)
  File "/usr/lib/python2.7/dist-packages/rospkg/rospack.py", line 67, in list_by_path
    root = ElementTree(None, os.path.join(d, PACKAGE_FILE))
  File "/usr/lib/python2.7/xml/etree/ElementTree.py", line 611, in __init__
    self.parse(file)
  File "<string>", line 38, in parse
cElementTree.ParseError: no element found: line 1, column 0
RLException: Invalid <param> tag: Cannot load command parameter [rosversion]: command [rosversion roslaunch] returned with code [1]. 

Param xml is <param command="rosversion roslaunch" name="rosversion"/>
The traceback for the exception was written to the log file
No handlers could be found for logger "roslaunch"