Oppo google contacts/calendar doesn't sync, experiencing some problems

[Android Central Question]

just contacts and calendar dont sync, always showing "experiencing some problems.......", backed up all contacts just in case, reinstalled google contacts but the syncing process is taking too long, i think it is just stuck.
please help
now changed the default to my gmail account but still waiting for the syncing..
Heeeelp

 

[B. Diddy]

Welcome to Android Central! If all of your contacts and calendar events are already safely in your Google cloud (i.e., you can see them in the desktop browser sites for Contacts and Calendar), then go to Settings>Apps, tap Menu>Show System, and select Contact Storage and Calendar Storage. Clear Cache/Data for both of them. Now see if the sync goes through.