`connect to private/policy-spf: No such file or directory` when receive mail by postfix in centos 7

My system is centos 7 with postfix,dovecot,pypolicyd-spf, opendkim.
I can send mail but cannot receive mail,

I notice warnings as below:

Feb  6 20:01:09 srv-8327 postfix/smtpd[20391]: warning: connect to private/policy-spf: No such file or directory
Feb  6 20:01:09 srv-8327 postfix/smtpd[20391]: warning: problem talking to server private/policy-spf: No such file or directory
Feb  6 20:01:10 srv-8327 postfix/smtpd[20391]: warning: connect to private/policy-spf: No such file or directory
Feb  6 20:01:10 srv-8327 postfix/smtpd[20391]: warning: problem talking to server private/policy-spf: No such file or directory

I already set debugLevel = 4 in /etc/python-policyd-spf/policyd-spf.conf.
How to find the problem of python-policyd-spf?

Plus:
I finally solve this problem:
In the /etc/postfix/main.cf, I change unix:private/policy to unix:private/policyd-spf,bingo!

smtpd_recipient_restrictions = permit_mynetworks,permit_sasl_authenticated,reject_unauth_destination,check_policy_service unix:private/policyd-spf,reject_invalid_hostname,reject_non_fqdn_helo_hostname,reject_non_fqdn_sender,reject_non_fqdn_recipient

I finally solve this problem:
In the /etc/postfix/main.cf, change unix:private/policy to unix:private/policyd-spf,bingo!