diff --git a/rs/https_outcalls/consensus/src/payload_builder.rs b/rs/https_outcalls/consensus/src/payload_builder.rs
index 61d5b4bed932..d6e2ca3223f3 100644
--- a/rs/https_outcalls/consensus/src/payload_builder.rs
+++ b/rs/https_outcalls/consensus/src/payload_builder.rs
@@ -658,6 +658,18 @@ impl CanisterHttpPayloadBuilderImpl {
                     );
                 }
 
+                // Rejects are not allowed in flexible ok-responses
+                if matches!(
+                    entry.response.content,
+                    CanisterHttpResponseContent::Reject(_)
+                ) {
+                    return invalid_artifact(
+                        InvalidCanisterHttpPayloadReason::FlexibleRejectNotAllowedInOkResponses {
+                            callback_id,
+                        },
+                    );
+                }
+
                 // No duplicate signers
                 let signer = entry.proof.signature.signer;
                 if !seen_signers.insert(signer) {
diff --git a/rs/https_outcalls/consensus/src/payload_builder/tests.rs b/rs/https_outcalls/consensus/src/payload_builder/tests.rs
index 7ca409997211..786576661506 100644
--- a/rs/https_outcalls/consensus/src/payload_builder/tests.rs
+++ b/rs/https_outcalls/consensus/src/payload_builder/tests.rs
@@ -1809,6 +1809,54 @@ fn flexible_build_respects_max_responses_per_block() {
     });
 }
 
+#[test]
+fn flexible_build_filters_rejects_in_ok_responses() {
+    let num_nodes = 4;
+    let committee: BTreeSet<_> = (0..num_nodes as u64).map(node_test_id).collect();
+    let callback_id = CallbackId::from(42);
+
+    setup_test_with_flexible_context(num_nodes, callback_id, committee, 2, 4, |pb, pool| {
+        {
+            use ic_types::canister_http::CanisterHttpReject;
+
+            let mut pool_access = pool.write().unwrap();
+            // Nodes 0 and 1 produce Reject responses
+            for node_idx in 0..2_u64 {
+                let (response, metadata) = test_response_and_metadata_with_content(
+                    callback_id.get(),
+                    CanisterHttpResponseContent::Reject(CanisterHttpReject {
+                        reject_code: RejectCode::SysTransient,
+                        message: format!("error_{node_idx}"),
+                    }),
+                );
+                let share = metadata_to_share(node_idx, &metadata);
+                add_own_share_to_pool(pool_access.deref_mut(), &share, &response);
+            }
+            // Nodes 2 and 3 produce Success responses
+            for node_idx in 2..4_u64 {
+                let (response, metadata) = test_response_and_metadata_with_content(
+                    callback_id.get(),
+                    CanisterHttpResponseContent::Success(format!("resp_{node_idx}").into_bytes()),
+                );
+                let share = metadata_to_share(node_idx, &metadata);
+                add_own_share_to_pool(pool_access.deref_mut(), &share, &response);
+            }
+        }
+
+        let parsed = build_and_validate_and_parse_payload(&pb);
+
+        assert_eq!(parsed.flexible_responses.len(), 1);
+        let group = &parsed.flexible_responses[0];
+        assert_eq!(group.responses.len(), 2);
+        for entry in &group.responses {
+            assert!(matches!(
+                entry.response.content,
+                CanisterHttpResponseContent::Success(_)
+            ));
+        }
+    });
+}
+
 #[test]
 fn flexible_build_and_validate_round_trip() {
     let num_nodes = 4;
@@ -2361,6 +2409,40 @@ fn flexible_invalid_unknown_callback_id() {
     });
 }
 
+#[test]
+fn flexible_invalid_rejects_in_ok_responses() {
+    let committee: BTreeSet<_> = (0..4).map(node_test_id).collect();
+    let callback_id = CallbackId::from(42);
+
+    setup_test_with_flexible_context(4, callback_id, committee, 2, 4, |payload_builder, _pool| {
+        let payload = flexible_payload(vec![FlexibleCanisterHttpResponses {
+            callback_id,
+            responses: vec![
+                flexible_response(42, 0, b"good_response"),
+                flexible_reject_response(42, 1),
+                flexible_response(42, 2, b"another_good"),
+            ],
+        }]);
+
+        let result = payload_builder.validate_payload(
+            Height::from(1),
+            &test_proposal_context(&default_validation_context()),
+            &payload_to_bytes_max_4mb(payload),
+            &[],
+        );
+        assert_matches!(
+            result,
+            Err(ValidationError::InvalidArtifact(
+                InvalidPayloadReason::InvalidCanisterHttpPayload(
+                    InvalidCanisterHttpPayloadReason::FlexibleRejectNotAllowedInOkResponses {
+                        callback_id: id,
+                    },
+                ),
+            )) if id == CallbackId::from(42)
+        );
+    });
+}
+
 #[test]
 fn flexible_invalid_callback_id_mismatch_in_response() {
     let committee: BTreeSet<_> = (0..4).map(node_test_id).collect();
@@ -2683,6 +2765,25 @@ fn flexible_response(
     }
 }
 
+fn flexible_reject_response(
+    callback_id: u64,
+    signer_node: u64,
+) -> FlexibleCanisterHttpResponseWithProof {
+    use ic_types::canister_http::CanisterHttpReject;
+
+    let (response, metadata) = test_response_and_metadata_with_content(
+        callback_id,
+        CanisterHttpResponseContent::Reject(CanisterHttpReject {
+            reject_code: RejectCode::SysTransient,
+            message: "could not connect".to_string(),
+        }),
+    );
+    FlexibleCanisterHttpResponseWithProof {
+        response,
+        proof: metadata_to_share(signer_node, &metadata),
+    }
+}
+
 fn flexible_payload(groups: Vec<FlexibleCanisterHttpResponses>) -> CanisterHttpPayload {
     CanisterHttpPayload {
         responses: vec![],
diff --git a/rs/https_outcalls/consensus/src/payload_builder/utils.rs b/rs/https_outcalls/consensus/src/payload_builder/utils.rs
index f4efbc7df31c..dd6a5d1bf849 100644
--- a/rs/https_outcalls/consensus/src/payload_builder/utils.rs
+++ b/rs/https_outcalls/consensus/src/payload_builder/utils.rs
@@ -5,8 +5,8 @@ use ic_types::{
         FlexibleCanisterHttpResponseWithProof, FlexibleCanisterHttpResponses, ValidationContext,
     },
     canister_http::{
-        CanisterHttpResponse, CanisterHttpResponseMetadata, CanisterHttpResponseShare,
-        CanisterHttpResponseWithConsensus,
+        CanisterHttpResponse, CanisterHttpResponseContent, CanisterHttpResponseMetadata,
+        CanisterHttpResponseShare, CanisterHttpResponseWithConsensus,
     },
     crypto::crypto_hash,
     messages::CallbackId,
@@ -217,10 +217,11 @@ pub(crate) fn find_non_replicated_response(
     })
 }
 
-/// Collects distinct HTTP outcall responses from flexible committee members.
+/// Collects distinct HTTP outcall OK-responses from flexible committee members.
 ///
-/// Gathers up to `max_responses` individually-signed `(response, share)` pairs
-/// from unique committee members, skipping any that would exceed `max_payload_size`.
+/// Gathers up to `max_responses` individually-signed `(ok-response, share)` pairs
+/// from unique committee members while disregarding rejects, and skipping any
+/// that would exceed `max_payload_size`.
 /// Returns the group and its accumulated byte size if at least `min_responses`
 /// were collected.
 pub(crate) fn find_flexible_responses(
@@ -250,6 +251,13 @@ pub(crate) fn find_flexible_responses(
             if let Some(http_response) =
                 pool_access.get_response_content_by_hash(&metadata.content_hash)
             {
+                if matches!(
+                    http_response.content,
+                    CanisterHttpResponseContent::Reject(_)
+                ) {
+                    // Disregard rejects, as we are collecting ok-responses.
+                    continue;
+                }
                 let response = FlexibleCanisterHttpResponseWithProof {
                     response: http_response,
                     proof: (*share).clone(),
diff --git a/rs/interfaces/src/canister_http.rs b/rs/interfaces/src/canister_http.rs
index a8026d6eadfb..9ab2b16efe5d 100644
--- a/rs/interfaces/src/canister_http.rs
+++ b/rs/interfaces/src/canister_http.rs
@@ -92,6 +92,10 @@ pub enum InvalidCanisterHttpPayloadReason {
         callback_id: CallbackId,
         signer: NodeId,
     },
+    /// A flexible ok-response group contains a Reject response.
+    FlexibleRejectNotAllowedInOkResponses {
+        callback_id: CallbackId,
+    },
     /// The payload is not in its designated section.
     /// For example, a non-flexible response is not in the responses section
     /// or a flexible response is not in the flexible_responses section.