Incompatible control file version.

After a site shutdown to enable power supply work, the database instance did not restart throwing the following error:
SQL> startup
ORACLE instance started.

Total System Global Area 6442450944 bytes
Fixed Size                  8635096 bytes
Variable Size            4462742824 bytes
Database Buffers         1962934272 bytes
Redo Buffers                8138752 bytes
ORA-00201: control file version 12.2.0.0.0 incompatible with ORACLE version 12.1.0.2.0
ORA-00202: control file: '/raid2/oradata/WLA/control01.ctl'

The database had been upgraded from 12.1.0.2 to 12.2.0.1  at the beginning of the year and been running normally apparently,
until the site shutdown and restart.  Forced a restart using startup pfile = '/raid1/packages/linux/oracle/product/12.2.0.1/dbs/pfileWLA.ora' ;
which works.

shutdown immediate and restart to see it throw the same error.  Checking I noticed that the  initWLA.ora file has a compatible=12.1.0.2.0 flag