ORA-04031: Unable to allocate N bytes of shared memory

What does it mean?

Oracle could not allocate contiguous memory of the requested size in a shared memory pool (usually the shared pool or large pool). An SGA component is under memory pressure.

Why does it happen?

Shared pool fragmentation due to many unique SQL statements without bind variables (full of literals), insufficient SHARED_POOL_SIZE, too many concurrent connections, large PL/SQL packages, or incorrect ASMM/AMM sizing.

How to fix it

Check which pool the error message refers to (shared pool, large pool, etc.). Short term: ALTER SYSTEM FLUSH SHARED_POOL (caution: in production this forces all SQL to be re-parsed, i.e. a temporary hard parse storm, and does not fix fragmentation permanently). Permanent fix: enforce bind variable usage (including CURSOR_SHARING), increase SGA_TARGET / SHARED_POOL_SIZE / LARGE_POOL_SIZE. Pin frequently used packages in memory with DBMS_SHARED_POOL.KEEP. Examine memory distribution with V$SGASTAT.