Windows error 8415 (ERROR_DS_SCHEMA_ALLOC

Status / error code:		Category:

Constant name:
Source:		Operating System:
Description: The directory service could not allocate memory required for schema state.

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ERROR_DS_SCHEMA_NOT_LOADED	ERROR_DS_ATT_SCHEMA_REQ_SYNTAX

ERROR_DS_SCHEMA_ALLOC_FAILED

Schema construction failed because local allocation could not complete

This status is a local resource failure in the schema subsystem. Active Directory needs memory to build and maintain its in-memory representation of classes, attributes, identifiers, and relationships. An allocation failure can prevent schema loading or recalculation even when the definitions stored in the schema NC are logically valid.

Check the domain controller process and system resource state at the exact time of the event. A single low-memory snapshot after recovery is not enough; correlate commit pressure, process termination, and adjacent Directory Service events. If the error appears only during a large custom schema import, also review the extension for abnormal scale or repeated definitions, but do not rewrite schema semantics solely because memory allocation failed.

What to inspect

Correlate the event with system memory and commit pressure on the domain controller.
Check whether schema cache rebuild or a large schema update was active at the time.
Preserve the first allocation and schema events before restarting the directory service.

References

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