if you see this message in ggserr.log for extract 

2020-08-25T18:14:41.778+0100  ERROR   OGG-00446  Oracle GoldenGate Capture for Oracle, e1.prm:  No valid log files for current redo sequence 88837, thread 1, error retrieving redo file name for sequence 88837, archived = 0, use_alternate = 0Not able to establish initial position for begin time 2020-08-25 18:09:32.000000.

then add below parameter in extract parameter file

TRANLOGOPTIONS DBLOGREADER