Error on update on backup

some one knows what’s this error on update

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
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 716, in call
return self.main(*args, **kwargs)
File “/home/frappe/frappe-bench/env/local/lib/python2.7/site-packages/click/core.py”, line 696, in main
rv = self.invoke(ctx)
File “/home/frappe/frappe-bench/env/local/lib/python2.7/site-packages/click/core.py”, line 1060, 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 1060, 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 889, 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 534, in invoke
return callback(*args, **kwargs)
File “/home/frappe/frappe-bench/env/local/lib/python2.7/site-packages/click/decorators.py”, line 17, in new_func
return f(get_current_context(), *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 292, in backup
frappe.init(site=site)
File “/home/frappe/frappe-bench/apps/frappe/frappe/init.py”, line 135, in init
local.conf = _dict(get_site_config())
File “/home/frappe/frappe-bench/apps/frappe/frappe/init.py”, line 189, in get_site_config
config.update(get_file_json(site_config))
File “/home/frappe/frappe-bench/apps/frappe/frappe/init.py”, line 896, in get_file_json
return json.load(f)
File “/usr/lib/python2.7/json/init.py”, line 290, in load
**kw)
File “/usr/lib/python2.7/json/init.py”, line 338, in loads
return _default_decoder.decode(s)
File “/usr/lib/python2.7/json/decoder.py”, line 366, in decode
obj, end = self.raw_decode(s, idx=_w(s, 0).end())
File “/usr/lib/python2.7/json/decoder.py”, line 382, in raw_decode
obj, end = self.scan_once(s, idx)
ValueError: Expecting property name: line 2 column 2 (char 3)

Check this,