Please help. Unable to switch to Develop

Install / Update
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Please help unable to switch to develop

root@cctvph:~# bench switch-to-develop
Traceback (most recent call last):
  File "/usr/local/bin/bench", line 9, in <module>
    load_entry_point('bench==0.1', 'console_scripts', 'bench')()
  File "/home/frappe/bench-repo/bench/cli.py", line 55, in cli
    bench()
  File "/usr/local/lib/python2.7/dist-packages/click/core.py", line 610, in __call__
    return self.main(*args, **kwargs)
  File "/usr/local/lib/python2.7/dist-packages/click/core.py", line 590, in main
    rv = self.invoke(ctx)
  File "/usr/local/lib/python2.7/dist-packages/click/core.py", line 936, in invoke
    return _process_result(sub_ctx.command.invoke(sub_ctx))
  File "/usr/local/lib/python2.7/dist-packages/click/core.py", line 782, in invoke
    return ctx.invoke(self.callback, **ctx.params)
  File "/usr/local/lib/python2.7/dist-packages/click/core.py", line 416, in invoke
    return callback(*args, **kwargs)
  File "/home/frappe/bench-repo/bench/cli.py", line 303, in _switch_to_develop
    switch_to_develop(upgrade=upgrade)
  File "/home/frappe/bench-repo/bench/app.py", line 170, in switch_to_develop
    switch_branch('develop', apps=apps, bench=bench, upgrade=upgrade)
  File "/home/frappe/bench-repo/bench/app.py", line 147, in switch_branch
    raise MajorVersionUpgradeException("Switching to {0} will cause upgrade from {1} to {2}".format(branch, version_upgrade[0], version_upgrade[1]), version_upgrade[0], version_upgrade[1])
bench.app.MajorVersionUpgradeException: Switching to develop will cause upgrade from 4 to 5
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