diff --git a/airbyte-cdk/bulk/toolkits/load-object-storage/src/main/kotlin/io/airbyte/cdk/load/state/object_storage/ObjectStorageDestinationStateManager.kt b/airbyte-cdk/bulk/toolkits/load-object-storage/src/main/kotlin/io/airbyte/cdk/load/state/object_storage/ObjectStorageDestinationStateManager.kt
index da8b5df5f871..2a6dd6e296b0 100644
--- a/airbyte-cdk/bulk/toolkits/load-object-storage/src/main/kotlin/io/airbyte/cdk/load/state/object_storage/ObjectStorageDestinationStateManager.kt
+++ b/airbyte-cdk/bulk/toolkits/load-object-storage/src/main/kotlin/io/airbyte/cdk/load/state/object_storage/ObjectStorageDestinationStateManager.kt
@@ -4,6 +4,7 @@
 
 package io.airbyte.cdk.load.state.object_storage
 
+import com.fasterxml.jackson.annotation.JsonIgnore
 import com.fasterxml.jackson.annotation.JsonProperty
 import edu.umd.cs.findbugs.annotations.SuppressFBWarnings
 import io.airbyte.cdk.load.command.DestinationStream
@@ -23,6 +24,8 @@ import java.nio.file.Paths
 import java.util.concurrent.ConcurrentHashMap
 import kotlinx.coroutines.flow.mapNotNull
 import kotlinx.coroutines.flow.toList
+import kotlinx.coroutines.sync.Mutex
+import kotlinx.coroutines.sync.withLock
 
 @SuppressFBWarnings("NP_NONNULL_PARAM_VIOLATION", justification = "Kotlin async continuation")
 class ObjectStorageDestinationState(
@@ -37,6 +40,8 @@ class ObjectStorageDestinationState(
         FINALIZED
     }
 
+    @JsonIgnore private val countByKeyLock = Mutex()
+
     companion object {
         const val METADATA_GENERATION_ID_KEY = "ab-generation-id"
         const val STREAM_NAMESPACE_KEY = "ab-stream-namespace"
@@ -121,7 +126,11 @@ class ObjectStorageDestinationState(
 
     /** Used to guarantee the uniqueness of a key */
     suspend fun ensureUnique(key: String): String {
-        val ordinal = countByKey.merge(key, 0L) { old, new -> maxOf(old + 1, new) } ?: 0L
+        val ordinal =
+            countByKeyLock.withLock {
+                countByKey.merge(key, 0L) { old, new -> maxOf(old + 1, new) }
+            }
+                ?: 0L
         return if (ordinal > 0L) {
             "$key-$ordinal"
         } else {
diff --git a/airbyte-integrations/connectors/destination-s3/build.gradle b/airbyte-integrations/connectors/destination-s3/build.gradle
index 5b83c46c6525..3fd620b31e5a 100644
--- a/airbyte-integrations/connectors/destination-s3/build.gradle
+++ b/airbyte-integrations/connectors/destination-s3/build.gradle
@@ -6,7 +6,7 @@ plugins {
 airbyteBulkConnector {
     core = 'load'
     toolkits = ['load-s3', 'load-avro']
-    cdk = '0.254'
+    cdk = 'local'
 }
 
 application {
diff --git a/airbyte-integrations/connectors/destination-s3/metadata.yaml b/airbyte-integrations/connectors/destination-s3/metadata.yaml
index 04640037c2df..78e246bb1cf0 100644
--- a/airbyte-integrations/connectors/destination-s3/metadata.yaml
+++ b/airbyte-integrations/connectors/destination-s3/metadata.yaml
@@ -2,7 +2,7 @@ data:
   connectorSubtype: file
   connectorType: destination
   definitionId: 4816b78f-1489-44c1-9060-4b19d5fa9362
-  dockerImageTag: 1.5.0-rc.4
+  dockerImageTag: 1.5.0-rc.5
   dockerRepository: airbyte/destination-s3
   githubIssueLabel: destination-s3
   icon: s3.svg
diff --git a/airbyte-integrations/connectors/destination-s3/src/main/kotlin/S3V2Checker.kt b/airbyte-integrations/connectors/destination-s3/src/main/kotlin/S3V2Checker.kt
index c445eb199086..46f5cf926a20 100644
--- a/airbyte-integrations/connectors/destination-s3/src/main/kotlin/S3V2Checker.kt
+++ b/airbyte-integrations/connectors/destination-s3/src/main/kotlin/S3V2Checker.kt
@@ -50,8 +50,7 @@ class S3V2Checker<T : OutputStream>(private val timeProvider: TimeProvider) :
                 log.info { "Successfully wrote test file: $results" }
             } finally {
                 s3Object?.also { s3Client.delete(it) }
-                val results = s3Client.list(path).toList()
-                log.info { "Successfully removed test tile: $results" }
+                log.info { "Successfully removed test file" }
             }
         }
     }
diff --git a/docs/integrations/destinations/s3.md b/docs/integrations/destinations/s3.md
index 77525f24e443..0e566ffdfec8 100644
--- a/docs/integrations/destinations/s3.md
+++ b/docs/integrations/destinations/s3.md
@@ -544,6 +544,7 @@ To see connector limitations, or troubleshoot your S3 connector, see more [in ou
 
 | Version    | Date       | Pull Request                                               | Subject                                                                                                                                              |
 |:-----------|:-----------|:-----------------------------------------------------------|:-----------------------------------------------------------------------------------------------------------------------------------------------------|
+| 1.5.0-rc.5 | 2025-01-06 | [50954](https://github.com/airbytehq/airbyte/pull/50954)   | Bug fix: transient failure due to bug in filename clash prevention                                                                                   |
 | 1.5.0-rc.4 | 2025-01-06 | [50954](https://github.com/airbytehq/airbyte/pull/50954)   | Bug fix: StreamLoader::close dispatched multiple times per stream                                                                                    |
 | 1.5.0-rc.3 | 2025-01-06 | [50949](https://github.com/airbytehq/airbyte/pull/50949)   | Bug fix: parquet types/values nested in union of objects do not convert properly                                                                     |
 | 1.5.0-rc.2 | 2025-01-02 | [50857](https://github.com/airbytehq/airbyte/pull/50857)   | Migrate to Bulk Load CDK: cost reduction, perf increase, bug fix for filename clashes                                                                |