ORA-00371: not enough shared pool memory, should be at least 16341008384 byte

SQL> startup pfile=initaux.ora  ORA-00371: not enough shared pool memory, should be at least 16341008384 bytes

Whenever we start an oracle database instance, it requires memory to allocate some memory components of the SGA so that instance could serve the database and database sessions. If we do not specify size of memory components, we might face errors during instance startup. sga_target is the basing parameter to specify before we start an instance and other memory components like shared pool, buffer cache, or log buffer cache are allocated from the memory allocated to SGA.

I was trying to start an auxiliary instance to build a standby database from live database and faced the above error. Normally there is no need to specify sga_target to start an auxiliary instance, however, this was because of a bug (as per MOS) and solution in this case is to specify sga_target in the init file being used to start auxiliary instance.  

Although suggested value sga_target was 5G, however, it also did not work and there was another error suggesting to set sga_target to at least 12G, which I did. After that, issue got resolved and I was able to start auxiliary instance without any issue.