From e6f9b31466e7c86a177bca7bbde11fe3f31c2402 Mon Sep 17 00:00:00 2001
From: Aleksander Sekowski <kontakt.sekowski@gmail.com>
Date: Mon, 26 Oct 2026 17:07:28 -0700
Subject: [PATCH] Core: handle missing bidder entries when merging rejection
 trackers

---
 .../server/auction/ExchangeService.java       |  2 ++
 .../server/auction/ExchangeServiceTest.java   | 28 +++++++++++++++++++
 2 files changed, 30 insertions(+)

diff --git a/src/main/java/org/prebid/server/auction/ExchangeService.java b/src/main/java/org/prebid/server/auction/ExchangeService.java
index 9860ae553df..e47a36f94dd 100644
--- a/src/main/java/org/prebid/server/auction/ExchangeService.java
+++ b/src/main/java/org/prebid/server/auction/ExchangeService.java
@@ -1378,6 +1378,8 @@ private void mergeBidRejectionTrackers(AuctionContext auctionContext,
                                            Map<String, Future<BidderResponse>> bidderToFutureResponse) {
 
         final Map<String, BidRejectionTracker> mergedBidRejectionTrackers = newBidRejectionTrackers.keySet().stream()
+                .filter(bidder -> bidderToFutureResponse.containsKey(bidder)
+                        || auctionContext.getBidRejectionTrackers().containsKey(bidder))
                 .collect(Collectors.toMap(Function.identity(), bidder -> mergeBidRejectionTrackersForSingleBidder(
                         bidderToFutureResponse.get(bidder),
                         auctionContext.getBidRejectionTrackers().get(bidder),
diff --git a/src/test/java/org/prebid/server/auction/ExchangeServiceTest.java b/src/test/java/org/prebid/server/auction/ExchangeServiceTest.java
index b37d908f286..43b902e2e2f 100644
--- a/src/test/java/org/prebid/server/auction/ExchangeServiceTest.java
+++ b/src/test/java/org/prebid/server/auction/ExchangeServiceTest.java
@@ -4544,6 +4544,34 @@ public void shouldFallBackToAccountLevelSecondaryBiddersWhenRequestLevelIsAbsent
         assertThat(result.succeeded()).isTrue();
     }
 
+    @Test
+    public void shouldIgnoreCopiedBidRejectionTrackersWithoutOriginalTrackerOrBidderFuture() {
+        // given
+        given(bidderRequestPostProcessor.process(any(), any(), any()))
+                .willAnswer(invocation -> {
+                    final AuctionContext bidderContext = invocation.getArgument(2);
+                    bidderContext.getBidRejectionTrackers().put("copiedOnlyBidder",
+                            new BidRejectionTracker("copiedOnlyBidder", Set.of("impId1"), 0.0));
+                    return Future.succeededFuture(
+                            BidderRequestPostProcessingResult.withValue(invocation.getArgument(0)));
+                });
+        doReturn(Future.succeededFuture(givenSeatBid(emptyList()))).when(httpBidderRequester)
+                .requestBids(any(), any(), any(), any(), any(), any(), anyBoolean());
+
+        final BidRequest bidRequest = givenBidRequest(givenSingleImp(Map.of("testBidder", 1)));
+        final AuctionContext auctionContext = givenRequestContext(bidRequest);
+
+        // when
+        final Future<AuctionContext> result = target.holdAuction(auctionContext);
+
+        // then
+        assertThat(result.succeeded()).isTrue();
+        assertThat(result.result().getBidRejectionTrackers()).containsOnlyKeys("testBidder");
+        assertThat(result.result().getBidRejectionTrackers().get("testBidder").getRejected())
+                .extracting(Rejection::reason)
+                .containsExactly(BidRejectionReason.NO_BID);
+    }
+
     @Test
     public void shouldRetainBidRejectionsForBiddersThatWereRejectedBeforeBidderFutureSplit() {
         // given