Server Error on PAypal Checkout

Getting this error upon paypal checkout:

Traceback (innermost last):
File “/home/frappe/frappe-bench/apps/frappe/frappe/app.py”, line 60, in application
response = frappe.api.handle()
File “/home/frappe/frappe-bench/apps/frappe/frappe/api.py”, line 50, in handle
return frappe.handler.handle()
File “/home/frappe/frappe-bench/apps/frappe/frappe/handler.py”, line 19, in handle
execute_cmd(cmd)
File “/home/frappe/frappe-bench/apps/frappe/frappe/handler.py”, line 36, in execute_cmd
ret = frappe.call(method, **frappe.form_dict)
File “/home/frappe/frappe-bench/apps/frappe/frappe/init.py”, line 805, in call
return fn(*args, **newargs)
File “/home/frappe/frappe-bench/apps/erpnext/erpnext/accounts/doctype/payment_request/payment_request.py”, line 200, in make_payment_request
generate_payment_request(pr.name)
File “/home/frappe/frappe-bench/apps/erpnext/erpnext/accounts/doctype/payment_request/payment_request.py”, line 259, in generate_payment_request
frappe.get_doc(“Payment Request”, name).run_method(“get_payment_url”)
File “/home/frappe/frappe-bench/apps/frappe/frappe/model/document.py”, line 579, in run_method
return Document.hook(fn)(self, *args, **kwargs)
File “/home/frappe/frappe-bench/apps/frappe/frappe/model/document.py”, line 735, in composer
return composed(self, method, *args, **kwargs)
File “/home/frappe/frappe-bench/apps/frappe/frappe/model/document.py”, line 720, in runner
add_to_return_value(self, f(self, method, *args, **kwargs))
File “/home/frappe/frappe-bench/apps/paypal_integration/paypal_integration/utils.py”, line 8, in get_payment_url
set_express_checkout(doc.grand_total, doc.currency, {“doctype”: doc.doctype, “docname”: doc.name})
File “/home/frappe/frappe-bench/apps/paypal_integration/paypal_integration/express_checkout.py”, line 29, in set_express_checkout
response = execute_set_express_checkout(amount, currency)
File “/home/frappe/frappe-bench/apps/paypal_integration/paypal_integration/express_checkout.py”, line 72, in execute_set_express_checkout
return get_api_response(params.encode(“utf-8”))
File “/home/frappe/frappe-bench/apps/paypal_integration/paypal_integration/express_checkout.py”, line 162, in get_api_response
s = get_request_session()
File “/home/frappe/frappe-bench/apps/frappe/frappe/utils/init.py”, line 368, in get_request_session
from requests.packages.urllib3.util import Retry
ImportError: cannot import name Retry

Try cd /home/frappe/frappe-bench && ./env/bin/pip install --upgrade -r apps/frappe/requirements.txt

It worked. Thanks.