diff --git a/src/config/sessions/targets.test.ts b/src/config/sessions/targets.test.ts
index f67bc10f8b9..68f25567558 100644
--- a/src/config/sessions/targets.test.ts
+++ b/src/config/sessions/targets.test.ts
@@ -3,7 +3,11 @@ import path from "node:path";
 import { describe, expect, it } from "vitest";
 import { withTempHome } from "../../../test/helpers/temp-home.js";
 import type { OpenClawConfig } from "../config.js";
-import { resolveAllAgentSessionStoreTargets, resolveSessionStoreTargets } from "./targets.js";
+import {
+  resolveAllAgentSessionStoreTargets,
+  resolveAllAgentSessionStoreTargetsSync,
+  resolveSessionStoreTargets,
+} from "./targets.js";
 
 describe("resolveSessionStoreTargets", () => {
   it("resolves all configured agent stores", () => {
@@ -209,4 +213,82 @@ describe("resolveAllAgentSessionStoreTargets", () => {
       );
     });
   });
+
+  it("skips unreadable or invalid discovery roots when other roots are still readable", async () => {
+    await withTempHome(async (home) => {
+      const customRoot = path.join(home, "custom-state");
+      await fs.mkdir(customRoot, { recursive: true });
+      await fs.writeFile(path.join(customRoot, "agents"), "not-a-directory", "utf8");
+
+      const envStateDir = path.join(home, "env-state");
+      const mainSessionsDir = path.join(envStateDir, "agents", "main", "sessions");
+      const retiredSessionsDir = path.join(envStateDir, "agents", "retired", "sessions");
+      await fs.mkdir(mainSessionsDir, { recursive: true });
+      await fs.mkdir(retiredSessionsDir, { recursive: true });
+      await fs.writeFile(path.join(mainSessionsDir, "sessions.json"), "{}", "utf8");
+      await fs.writeFile(path.join(retiredSessionsDir, "sessions.json"), "{}", "utf8");
+
+      const cfg: OpenClawConfig = {
+        session: {
+          store: path.join(customRoot, "agents", "{agentId}", "sessions", "sessions.json"),
+        },
+        agents: {
+          list: [{ id: "main", default: true }],
+        },
+      };
+      const env = {
+        ...process.env,
+        OPENCLAW_STATE_DIR: envStateDir,
+      };
+
+      await expect(resolveAllAgentSessionStoreTargets(cfg, { env })).resolves.toEqual(
+        expect.arrayContaining([
+          {
+            agentId: "retired",
+            storePath: path.join(retiredSessionsDir, "sessions.json"),
+          },
+        ]),
+      );
+    });
+  });
+});
+
+describe("resolveAllAgentSessionStoreTargetsSync", () => {
+  it("skips unreadable or invalid discovery roots when other roots are still readable", async () => {
+    await withTempHome(async (home) => {
+      const customRoot = path.join(home, "custom-state");
+      await fs.mkdir(customRoot, { recursive: true });
+      await fs.writeFile(path.join(customRoot, "agents"), "not-a-directory", "utf8");
+
+      const envStateDir = path.join(home, "env-state");
+      const mainSessionsDir = path.join(envStateDir, "agents", "main", "sessions");
+      const retiredSessionsDir = path.join(envStateDir, "agents", "retired", "sessions");
+      await fs.mkdir(mainSessionsDir, { recursive: true });
+      await fs.mkdir(retiredSessionsDir, { recursive: true });
+      await fs.writeFile(path.join(mainSessionsDir, "sessions.json"), "{}", "utf8");
+      await fs.writeFile(path.join(retiredSessionsDir, "sessions.json"), "{}", "utf8");
+
+      const cfg: OpenClawConfig = {
+        session: {
+          store: path.join(customRoot, "agents", "{agentId}", "sessions", "sessions.json"),
+        },
+        agents: {
+          list: [{ id: "main", default: true }],
+        },
+      };
+      const env = {
+        ...process.env,
+        OPENCLAW_STATE_DIR: envStateDir,
+      };
+
+      expect(resolveAllAgentSessionStoreTargetsSync(cfg, { env })).toEqual(
+        expect.arrayContaining([
+          {
+            agentId: "retired",
+            storePath: path.join(retiredSessionsDir, "sessions.json"),
+          },
+        ]),
+      );
+    });
+  });
 });
diff --git a/src/config/sessions/targets.ts b/src/config/sessions/targets.ts
index 659bd511a86..76b842d3dab 100644
--- a/src/config/sessions/targets.ts
+++ b/src/config/sessions/targets.ts
@@ -20,6 +20,15 @@ export type SessionStoreTarget = {
   storePath: string;
 };
 
+const NON_FATAL_DISCOVERY_ERROR_CODES = new Set([
+  "EACCES",
+  "ELOOP",
+  "ENOENT",
+  "ENOTDIR",
+  "EPERM",
+  "ESTALE",
+]);
+
 function dedupeTargetsByStorePath(targets: SessionStoreTarget[]): SessionStoreTarget[] {
   const deduped = new Map<string, SessionStoreTarget>();
   for (const target of targets) {
@@ -30,6 +39,11 @@ function dedupeTargetsByStorePath(targets: SessionStoreTarget[]): SessionStoreTa
   return [...deduped.values()];
 }
 
+function shouldSkipDiscoveryError(err: unknown): boolean {
+  const code = (err as NodeJS.ErrnoException | undefined)?.code;
+  return typeof code === "string" && NON_FATAL_DISCOVERY_ERROR_CODES.has(code);
+}
+
 function resolveSessionStoreDiscoveryState(
   cfg: OpenClawConfig,
   env: NodeJS.ProcessEnv,
@@ -71,7 +85,16 @@ export function resolveAllAgentSessionStoreTargetsSync(
   const env = params.env ?? process.env;
   const { configuredTargets, agentsRoots } = resolveSessionStoreDiscoveryState(cfg, env);
   const discoveredTargets = toDiscoveredSessionStoreTargets(
-    agentsRoots.flatMap((agentsDir) => resolveAgentSessionDirsFromAgentsDirSync(agentsDir)),
+    agentsRoots.flatMap((agentsDir) => {
+      try {
+        return resolveAgentSessionDirsFromAgentsDirSync(agentsDir);
+      } catch (err) {
+        if (shouldSkipDiscoveryError(err)) {
+          return [];
+        }
+        throw err;
+      }
+    }),
   );
   return dedupeTargetsByStorePath([...configuredTargets, ...discoveredTargets]);
 }
@@ -84,7 +107,16 @@ export async function resolveAllAgentSessionStoreTargets(
   const { configuredTargets, agentsRoots } = resolveSessionStoreDiscoveryState(cfg, env);
 
   const discoveredDirs = await Promise.all(
-    agentsRoots.map((agentsDir) => resolveAgentSessionDirsFromAgentsDir(agentsDir)),
+    agentsRoots.map(async (agentsDir) => {
+      try {
+        return await resolveAgentSessionDirsFromAgentsDir(agentsDir);
+      } catch (err) {
+        if (shouldSkipDiscoveryError(err)) {
+          return [];
+        }
+        throw err;
+      }
+    }),
   );
   const discoveredTargets = toDiscoveredSessionStoreTargets(discoveredDirs.flat());
   return dedupeTargetsByStorePath([...configuredTargets, ...discoveredTargets]);
diff --git a/src/gateway/server-session-key.test.ts b/src/gateway/server-session-key.test.ts
index dfdec62f488..063a8bfe774 100644
--- a/src/gateway/server-session-key.test.ts
+++ b/src/gateway/server-session-key.test.ts
@@ -56,7 +56,9 @@ describe("resolveSessionKeyForRun", () => {
     expect(hoisted.loadCombinedSessionStoreForGatewayMock).toHaveBeenCalledWith(cfg);
   });
 
-  it("caches misses so repeated lookups do not rebuild the combined store", () => {
+  it("caches misses briefly before re-checking the combined store", () => {
+    vi.useFakeTimers();
+    vi.setSystemTime(new Date("2026-03-12T15:00:00Z"));
     hoisted.loadConfigMock.mockReturnValue({});
     hoisted.loadCombinedSessionStoreForGatewayMock.mockReturnValue({
       storePath: "(multiple)",
@@ -66,5 +68,11 @@ describe("resolveSessionKeyForRun", () => {
     expect(resolveSessionKeyForRun("missing-run")).toBeUndefined();
     expect(resolveSessionKeyForRun("missing-run")).toBeUndefined();
     expect(hoisted.loadCombinedSessionStoreForGatewayMock).toHaveBeenCalledTimes(1);
+
+    vi.advanceTimersByTime(1_001);
+
+    expect(resolveSessionKeyForRun("missing-run")).toBeUndefined();
+    expect(hoisted.loadCombinedSessionStoreForGatewayMock).toHaveBeenCalledTimes(2);
+    vi.useRealTimers();
   });
 });
diff --git a/src/gateway/server-session-key.ts b/src/gateway/server-session-key.ts
index aaa742acfa8..dd31a670c0f 100644
--- a/src/gateway/server-session-key.ts
+++ b/src/gateway/server-session-key.ts
@@ -4,7 +4,14 @@ import { toAgentRequestSessionKey } from "../routing/session-key.js";
 import { loadCombinedSessionStoreForGateway } from "./session-utils.js";
 
 const RUN_LOOKUP_CACHE_LIMIT = 256;
-const resolvedSessionKeyByRunId = new Map<string, string | null>();
+const RUN_LOOKUP_MISS_TTL_MS = 1_000;
+
+type RunLookupCacheEntry = {
+  sessionKey: string | null;
+  expiresAt: number | null;
+};
+
+const resolvedSessionKeyByRunId = new Map<string, RunLookupCacheEntry>();
 
 function setResolvedSessionKeyCache(runId: string, sessionKey: string | null): void {
   if (!runId) {
@@ -19,7 +26,10 @@ function setResolvedSessionKeyCache(runId: string, sessionKey: string | null): v
       resolvedSessionKeyByRunId.delete(oldest);
     }
   }
-  resolvedSessionKeyByRunId.set(runId, sessionKey);
+  resolvedSessionKeyByRunId.set(runId, {
+    sessionKey,
+    expiresAt: sessionKey === null ? Date.now() + RUN_LOOKUP_MISS_TTL_MS : null,
+  });
 }
 
 export function resolveSessionKeyForRun(runId: string) {
@@ -29,7 +39,13 @@ export function resolveSessionKeyForRun(runId: string) {
   }
   const cachedLookup = resolvedSessionKeyByRunId.get(runId);
   if (cachedLookup !== undefined) {
-    return cachedLookup ?? undefined;
+    if (cachedLookup.sessionKey !== null) {
+      return cachedLookup.sessionKey;
+    }
+    if ((cachedLookup.expiresAt ?? 0) > Date.now()) {
+      return undefined;
+    }
+    resolvedSessionKeyByRunId.delete(runId);
   }
   const cfg = loadConfig();
   const { store } = loadCombinedSessionStoreForGateway(cfg);