diff --git a/apps/server/src/share/routes.ts b/apps/server/src/share/routes.ts
index 80544fd998..69489c5522 100644
--- a/apps/server/src/share/routes.ts
+++ b/apps/server/src/share/routes.ts
@@ -1,6 +1,6 @@
 import safeCompare from "safe-compare";
 
-import type { Request, Response, Router } from "express";
+import type { NextFunction, Request, Response, Router } from "express";
 
 import shaca from "./shaca/shaca.js";
 import shacaLoader from "./shaca/shaca_loader.js";
@@ -10,6 +10,16 @@ import type SNote from "./shaca/entities/snote.js";
 import type SAttachment from "./shaca/entities/sattachment.js";
 import { getDefaultTemplatePath, renderNoteContent } from "./content_renderer.js";
 import utils from "../services/utils.js";
+import { isShareDbReady } from "./sql.js";
+
+function assertShareDbReady(_req: Request, res: Response, next: NextFunction) {
+    if (!isShareDbReady()) {
+        res.status(503).send("The application is still initializing. Please try again in a moment.");
+        return;
+    }
+
+    next();
+}
 
 function addNoIndexHeader(note: SNote, res: Response) {
     if (note.isLabelTruthy("shareDisallowRobotIndexing")) {
@@ -115,6 +125,8 @@ function render404(res: Response) {
 }
 
 function register(router: Router) {
+    // Guard: if the share DB is not yet initialized, return 503 for all /share routes.
+    router.use("/share", assertShareDbReady);
 
     function renderNote(note: SNote, req: Request, res: Response) {
         if (!note) {
diff --git a/apps/server/src/share/sql.ts b/apps/server/src/share/sql.ts
index 36cca4b5ec..5a127e791f 100644
--- a/apps/server/src/share/sql.ts
+++ b/apps/server/src/share/sql.ts
@@ -5,12 +5,14 @@ import dataDir from "../services/data_dir.js";
 import sql_init from "../services/sql_init.js";
 
 let dbConnection!: Database.Database;
+let dbConnectionReady = false;
 
 sql_init.dbReady.then(() => {
     dbConnection = new Database(dataDir.DOCUMENT_PATH, {
         readonly: true,
         nativeBinding: process.env.BETTERSQLITE3_NATIVE_PATH || undefined
     });
+    dbConnectionReady = true;
 
     [`exit`, `SIGINT`, `SIGUSR1`, `SIGUSR2`, `SIGTERM`].forEach((eventType) => {
         process.on(eventType, () => {
@@ -23,18 +25,31 @@ sql_init.dbReady.then(() => {
     });
 });
 
+function assertDbReady(): void {
+    if (!dbConnectionReady) {
+        throw new Error("Share database connection is not yet ready. The application may still be initializing.");
+    }
+}
+
 function getRawRows<T>(query: string, params = []): T[] {
+    assertDbReady();
     return dbConnection.prepare(query).raw().all(params) as T[];
 }
 
 function getRow<T>(query: string, params: string[] = []): T {
+    assertDbReady();
     return dbConnection.prepare(query).get(params) as T;
 }
 
 function getColumn<T>(query: string, params: string[] = []): T[] {
+    assertDbReady();
     return dbConnection.prepare(query).pluck().all(params) as T[];
 }
 
+export function isShareDbReady(): boolean {
+    return dbConnectionReady;
+}
+
 export default {
     getRawRows,
     getRow,