Error during update to 10.1.66

Dear all,

Got this error during update to v10.1.66. Can someone help me in resolving it?

Traceback (most recent call last):
  File "/usr/lib/python2.7/runpy.py", line 162, in _run_module_as_main
    "__main__", fname, loader, pkg_name)
  File "/usr/lib/python2.7/runpy.py", line 72, in _run_code
    exec code in run_globals
  File "/home/frappe/frappe-bench/apps/frappe/frappe/utils/bench_helper.py", line 94, in <module>
    main()
  File "/home/frappe/frappe-bench/apps/frappe/frappe/utils/bench_helper.py", line 18, in main
    click.Group(commands=commands)(prog_name='bench')
  File "/home/frappe/frappe-bench/env/local/lib/python2.7/site-packages/click/core.py", line 664, in __call__
    return self.main(*args, **kwargs)
  File "/home/frappe/frappe-bench/env/local/lib/python2.7/site-packages/click/core.py", line 644, in main
    rv = self.invoke(ctx)
  File "/home/frappe/frappe-bench/env/local/lib/python2.7/site-packages/click/core.py", line 991, in invoke
    return _process_result(sub_ctx.command.invoke(sub_ctx))
  File "/home/frappe/frappe-bench/env/local/lib/python2.7/site-packages/click/core.py", line 991, in invoke
    return _process_result(sub_ctx.command.invoke(sub_ctx))
  File "/home/frappe/frappe-bench/env/local/lib/python2.7/site-packages/click/core.py", line 837, in invoke
    return ctx.invoke(self.callback, **ctx.params)
  File "/home/frappe/frappe-bench/env/local/lib/python2.7/site-packages/click/core.py", line 464, in invoke
    return callback(*args, **kwargs)
  File "/home/frappe/frappe-bench/apps/frappe/frappe/commands/__init__.py", line 24, in _func
    ret = f(frappe._dict(ctx.obj), *args, **kwargs)
  File "/home/frappe/frappe-bench/apps/frappe/frappe/commands/site.py", line 215, in migrate
    from frappe.migrate import migrate
  File "/home/frappe/frappe-bench/apps/frappe/frappe/migrate.py", line 17, in <module>
    import frappe.utils.help
  File "/home/frappe/frappe-bench/apps/frappe/frappe/utils/help.py", line 14, in <module>
    from bs4 import BeautifulSoup
  File "/home/frappe/frappe-bench/env/local/lib/python2.7/site-packages/bs4/__init__.py", line 30, in <module>
    from .builder import builder_registry, ParserRejectedMarkup
  File "/home/frappe/frappe-bench/env/local/lib/python2.7/site-packages/bs4/builder/__init__.py", line 314, in <module>
    from . import _html5lib
  File "/home/frappe/frappe-bench/env/local/lib/python2.7/site-packages/bs4/builder/_html5lib.py", line 70, in <module>
    class TreeBuilderForHtml5lib(html5lib.treebuilders._base.TreeBuilder):
AttributeError: 'module' object has no attribute '_base'

Thanks,
Ahmed