PROBLEM:

While dropping a redolog group, got below error.

SOLUTION:

First, check the status of the redolog group.

Here the status of the redolog group, which are trying to drop is CURRENT. i.e This implies that the redo log is active. The redo log could be open or closed.

So we need to make the status of the redolog to INACTIVE. Switch logfile multiple times, till the status becomes INACTIVE.

As the status is INACTIVE now, we can drop it.