diff --git a/CHANGELOG.md b/CHANGELOG.md
index 85acbf7857..4be3ab58a2 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -15,6 +15,7 @@ Docs: https://docs.openclaw.ai
 
 ### Fixes
 
+- Model failover: treat HTTP 400 errors as failover-eligible, enabling automatic model fallback when providers return bad request errors. (#1879) Thanks @orenyomtov.
 - Exec approvals: format forwarded command text as inline/fenced monospace for safer approval scanning across channels. (#11937)
 - Config: clamp `maxTokens` to `contextWindow` to prevent invalid model configs. (#5516) Thanks @lailoo.
 - Docs: fix language switcher ordering and Japanese locale flag in Mintlify nav. (#12023) Thanks @joshp123.
diff --git a/src/agents/failover-error.test.ts b/src/agents/failover-error.test.ts
index a43ae289fd..d81781a905 100644
--- a/src/agents/failover-error.test.ts
+++ b/src/agents/failover-error.test.ts
@@ -11,6 +11,7 @@ describe("failover-error", () => {
     expect(resolveFailoverReasonFromError({ statusCode: "429" })).toBe("rate_limit");
     expect(resolveFailoverReasonFromError({ status: 403 })).toBe("auth");
     expect(resolveFailoverReasonFromError({ status: 408 })).toBe("timeout");
+    expect(resolveFailoverReasonFromError({ status: 400 })).toBe("format");
   });
 
   it("infers format errors from error messages", () => {
diff --git a/src/agents/failover-error.ts b/src/agents/failover-error.ts
index 3a100c324d..ddef897176 100644
--- a/src/agents/failover-error.ts
+++ b/src/agents/failover-error.ts
@@ -160,6 +160,9 @@ export function resolveFailoverReasonFromError(err: unknown): FailoverReason | n
   if (status === 408) {
     return "timeout";
   }
+  if (status === 400) {
+    return "format";
+  }
 
   const code = (getErrorCode(err) ?? "").toUpperCase();
   if (["ETIMEDOUT", "ESOCKETTIMEDOUT", "ECONNRESET", "ECONNABORTED"].includes(code)) {