QuickBooks errors can be very disturbing while you work on QuickBooks. Error code 387 is one of them, which can arise due to:
Malware attack or breakdown of firewall.
Some applications may be corrupt.

Ways to fix this error:
This error can be fixed by refreshing the system and then creating the invoice.
It can be done by going to customers tab in the QuickBooks and then opting the option of Create invoice.

Hopefully error code c=387 is now fixed. If you feel you are stuck and need assistance reach out to QBSsolved at +1(888) 910 1619.