What does Windows error code 781 (ERROR_INSUFFICIENT_RESOURCE_FOR_SPECIFIED_SHARED_SECTION_SIZE) mean?

ERROR_INSUFFICIENT_RESOURCE_FOR_SPECIFIED_SHARED_SECTION_SIZE

The desktop heap could not allocate session memory for the requested shared section.

ERROR_INSUFFICIENT_RESOURCE_FOR_SPECIFIED_SHARED_SECTION_SIZE means that the desktop heap could not allocate session memory for the requested shared section. Interactive Windows sessions use shared sections, commonly called desktop heap, for window-manager and USER objects. This code appears when the requested section size cannot be backed from the session resources available to the desktop or window station.

Where the result appears

• services or automation hosts that create many hidden desktops or window stations.
• Remote Desktop Session Host systems with many simultaneous sessions.
• GUI test farms that leak HWND, menu, hook, or desktop objects.
• process startup when a desktop heap setting is too large for the session layout.

What to collect

• session ID, window station, desktop name, and whether the process is interactive.
• USER and GDI object counts for long-running processes.
• the SharedSection values and any recent registry or policy modification.
• desktop creation counts, RDS session count, and the relevant event-log message.

Handling and recovery

First find leaks or unnecessary desktop creation. Increasing SharedSection values can move the limit but also consumes a finite session resource, so change it only after measuring the workload and validating the result under the expected number of sessions. Restarting a leaking process may restore capacity temporarily but is not a permanent fix.

Common misinterpretation

Adding system RAM alone may not solve this error. The exhausted resource is a specifically organized session shared section, not simply the machine-wide free-memory counter.

References

• Microsoft: System error codes 500–999