ImportError: No module named connections

I had run switch to master command and than bench update command and after this my site went of and getting error

ImportError: No module named connections

Traceback (most recent call last):
File “/home/arsalan/frappe-bench/apps/frappe/frappe/middlewares.py”, line 15, in call
return super(StaticDataMiddleware, self).call(environ, start_response)
File “/home/arsalan/frappe-bench/env/lib/python2.7/site-packages/werkzeug/wsgi.py”, line 600, in call
return self.app(environ, start_response)
File “/home/arsalan/frappe-bench/env/lib/python2.7/site-packages/werkzeug/wsgi.py”, line 600, in call
return self.app(environ, start_response)
File “/home/arsalan/frappe-bench/env/lib/python2.7/site-packages/werkzeug/local.py”, line 228, in application
return ClosingIterator(app(environ, start_response), self.cleanup)
File “/home/arsalan/frappe-bench/env/lib/python2.7/site-packages/werkzeug/wrappers.py”, line 301, in application
return f(*args[:-2] + (request,))(*args[-2:])
File “/home/arsalan/frappe-bench/apps/frappe/frappe/app.py”, line 83, in application
response = handle_exception(e)
File “/home/arsalan/frappe-bench/apps/frappe/frappe/app.py”, line 182, in handle_exception
http_status_code=http_status_code)
File “/home/arsalan/frappe-bench/apps/frappe/frappe/website/render.py”, line 72, in render
data = render_page(path)
File “/home/arsalan/frappe-bench/apps/frappe/frappe/website/render.py”, line 149, in render_page
return build(path)
File “/home/arsalan/frappe-bench/apps/frappe/frappe/website/render.py”, line 156, in build
return build_page(path)
File “/home/arsalan/frappe-bench/apps/frappe/frappe/website/render.py”, line 169, in build_page
context = get_context(path)
File “/home/arsalan/frappe-bench/apps/frappe/frappe/website/context.py”, line 28, in get_context
context = build_context(context)
File “/home/arsalan/frappe-bench/apps/frappe/frappe/website/context.py”, line 77, in build_context
context.update(get_website_settings())
File “/home/arsalan/frappe-bench/apps/frappe/frappe/website/doctype/website_settings/website_settings.py”, line 74, in get_website_settings
‘top_bar_items’: get_items(‘top_bar_items’),
File “/home/arsalan/frappe-bench/apps/frappe/frappe/website/doctype/website_settings/website_settings.py”, line 131, in get_items
order by idx asc""", parentfield, as_dict=1)
File “/home/arsalan/frappe-bench/apps/frappe/frappe/database.py”, line 121, in sql
self.connect()
File “/home/arsalan/frappe-bench/apps/frappe/frappe/database.py”, line 67, in connect
use_unicode=True, charset=‘utf8mb4’)
File “/home/arsalan/frappe-bench/env/local/lib/python2.7/site-packages/MySQLdb/init.py”, line 85, in Connect

ImportError: No module named connections

I am new and beginner in ERPNEXT, frappe and python

using healthcare

ok my site is up

i run command

bench migrate

in my bench-frappe folder