Both platforms have been experiencing a global outage for over 12 hours.
There are particular connectivity issues in the UK and US.
Facebook now claims to have resolved the issue, but users on Friday morning were still unable to post to the site. Other posts were reporting an unusually low reach rate.
In a statement Facebook said:
"Earlier today, a technical issue caused some people to have trouble connecting to Facebook and Instagram. We resolved this issue for everyone, and we apologise for any inconvenience.”