Oracle Message ORA-01617 - cannot mount: string is not a valid thread number

ERRORcannot mount: string is not a valid thread number
CAUSEThe INIT.ORA parameter thread is not between 1 and the number of threads allowed by the control file.
ACTIONShut down the instance, change the INIT.ORA parameter and startup, or resize the thread record and/or checkpoint progress record sections of the control file.