What causes "Failed to update default system prompt." in Mintplex-Labs/anything-llm?

Inspect server logs — the console.error in the catch logs the underlying error with its real message.

Mintplex-Labs/anything-llm · error · Error

Failed to update default system prompt.

Error message

Failed to update default system prompt.

What it means

Thrown by POST /system/default-system-prompt when SystemSettings.updateSettings returns { success: false }. The thrown Error uses error.message when present, falling back to this string only when the failure carried no message. updateSettings is the generic system-settings persistence layer (typically a DB upsert), so the real cause is whatever made that layer report failure.

Source

Thrown at server/endpoints/system.js:893

        console.error("Error fetching default system prompt:", error);
        response
          .status(500)
          .json({ success: false, message: "Internal server error" });
      }
    }
  );

  app.post(
    "/system/default-system-prompt",
    [validatedRequest, flexUserRoleValid([ROLES.admin])],
    async (request, response) => {
      try {
        const { defaultSystemPrompt } = reqBody(request);
        const { success, error } = await SystemSettings.updateSettings({
          default_system_prompt: defaultSystemPrompt,
        });
        if (!success)
          throw new Error(
            error.message || "Failed to update default system prompt."
          );
        response.status(200).json({
          success: true,
          message: "Default system prompt updated successfully.",
        });
      } catch (error) {
        console.error("Error updating default system prompt:", error);
        response.status(500).json({
          success: false,
          message: error.message || "Internal server error",
        });
      }
    }
  );

  app.delete(
    "/system/remove-pfp",

View on GitHub (pinned to 526360e320)

Solutions

Inspect server logs — the console.error in the catch logs the underlying error with its real message.
Confirm the database is reachable and the system_settings table exists (run migrations).
Reduce the prompt length and retry to rule out a size constraint.
If the inner error is transient (lock/timeout), retry the save.

Defensive patterns

Strategy: try-catch

Try / catch

try {
  const { success, error } = await SystemSettings.updateSettings({ default_system_prompt: prompt });
  if (!success) throw new Error(error?.message || 'updateSettings failed');
} catch (e) {
  logger.error('default-system-prompt update failed', { cause: e });
  res.status(500).json({ success: false, message: e.message });
}

Prevention

Log the inner error object to capture the real DB message.
Validate prompt length on the client to avoid DB size constraints.
Ensure migrations are applied so system_settings exists.

When it happens

Trigger: An admin saves a new default system prompt but the database write fails, a validation inside updateSettings rejects the value, or the settings table/row is locked or missing. The fallback text appears only when the inner error object had no message.

Common situations: Database connection dropped mid-request; the prompt text exceeded a column size limit; a migration left the system_settings table in an unexpected state; Prisma threw a constraint violation.

Related errors

AI-assisted analysis of Mintplex-Labs/anything-llm@526360e320 (2026-08-13). Data as JSON: /api/errors/687c3e2707712e3e. Report an issue: GitHub.