my current environment were the problem was faced in:

Oracle 12cR1 (12.1.0.2.180417)

Linux Red Hat 7.4

The following errors were thrown in the import (impdp) log file :

ORA-39014: One or more workers have prematurely exited.

ORA-39029: worker 1 with process name “DW00” prematurely terminated

ORA-31671: Worker process DW00 had an unhandled exception.

ORA-01000: maximum open cursors exceeded

ORA-06512: at “SYS.KUPC$QUEUE_INT”, line 254

ORA-06512: at “SYS.KUPW$WORKER”, line 2157

ORA-01000: maximum open cursors exceeded

ORA-06512: at “SYS.KUPW$WORKER”, line 4700

ORA-01000: maximum open cursors exceeded

ORA-06512: at “SYS.KUPW$WORKER”, line 23341

To resolve this problem …you have three options:

Apply ORACLE DATABASE Patch for Bug# 23278750 for Linux-x86-64 Platforms 

OR

Upgrade to 12.2.0.1 🙂

OR

 Set the OPEN_CURSORS parameter to a value equal to or greater than the total number of indexes being imported