diff --git a/app/src/test/java/org/thoughtcrime/securesms/groups/v2/processing/GroupsV2StateProcessorTest.kt b/app/src/test/java/org/thoughtcrime/securesms/groups/v2/processing/GroupsV2StateProcessorTest.kt
index dcd98bf6fe..1f288b3c89 100644
--- a/app/src/test/java/org/thoughtcrime/securesms/groups/v2/processing/GroupsV2StateProcessorTest.kt
+++ b/app/src/test/java/org/thoughtcrime/securesms/groups/v2/processing/GroupsV2StateProcessorTest.kt
@@ -7,6 +7,7 @@ import assertk.assertions.any
 import assertk.assertions.contains
 import assertk.assertions.isEqualTo
 import assertk.assertions.isNotNull
+import assertk.fail
 import io.mockk.every
 import io.mockk.justRun
 import io.mockk.mockk
@@ -70,6 +71,7 @@ import org.whispersystems.signalservice.api.groupsv2.ReceivedGroupSendEndorsemen
 import org.whispersystems.signalservice.api.push.ServiceId.ACI
 import org.whispersystems.signalservice.api.push.ServiceId.PNI
 import org.whispersystems.signalservice.api.push.ServiceIds
+import org.whispersystems.signalservice.api.push.exceptions.NonSuccessfulResponseCodeException
 import org.whispersystems.signalservice.internal.push.exceptions.NotInGroupException
 import java.io.IOException
 import java.util.Optional
@@ -1045,4 +1047,41 @@ class GroupsV2StateProcessorTest {
 
     assertThat(result.updateStatus, "inactive local is still updated given same revision from server").isEqualTo(GroupUpdateResult.UpdateStatus.GROUP_UPDATED)
   }
+
+  /**
+   * If we get a 500 back from the service we handle it gracefully.
+   */
+  @Test
+  fun ignore403sWithoutSignalTimestampHeader() {
+    given {
+      localState(
+        active = false,
+        revision = 5,
+        members = selfAndOthers
+      )
+      changeSet {
+        changeLog(6) {
+          change {
+            setNewTitle("new title")
+          }
+        }
+      }
+      apiCallParameters(requestedRevision = 5, includeFirst = false)
+      expectTableUpdate = false
+    }
+
+    every { groupsV2API.getGroupJoinedAt(any()) } returns NetworkResult.StatusCodeError(NonSuccessfulResponseCodeException(500))
+
+    try {
+      processor.updateLocalGroupToRevision(
+        targetRevision = GroupsV2StateProcessor.LATEST,
+        timestamp = 0
+      )
+    } catch (e: NonSuccessfulResponseCodeException) {
+      assertThat(e.code).isEqualTo(500)
+      return
+    }
+
+    fail("No exception thrown")
+  }
 }
diff --git a/libsignal-service/src/main/java/org/whispersystems/signalservice/internal/push/PushServiceSocket.java b/libsignal-service/src/main/java/org/whispersystems/signalservice/internal/push/PushServiceSocket.java
index 146d3eaf61..0602ba09a3 100644
--- a/libsignal-service/src/main/java/org/whispersystems/signalservice/internal/push/PushServiceSocket.java
+++ b/libsignal-service/src/main/java/org/whispersystems/signalservice/internal/push/PushServiceSocket.java
@@ -2910,10 +2910,18 @@ public class PushServiceSocket {
   }
 
   private static final ResponseCodeHandler GROUPS_V2_PUT_RESPONSE_HANDLER   = (responseCode, body, getHeader) -> {
+    if (getHeader.apply("X-Signal-Timestamp") == null) {
+      throw new NonSuccessfulResponseCodeException(500, "Missing timestamp header");
+    }
+
     if (responseCode == 409) throw new GroupExistsException();
   };
 
   private static final ResponseCodeHandler GROUPS_V2_GET_CURRENT_HANDLER    = (responseCode, body, getHeader) -> {
+    if (getHeader.apply("X-Signal-Timestamp") == null) {
+      throw new NonSuccessfulResponseCodeException(500, "Missing timestamp header");
+    }
+
     switch (responseCode) {
       case 403: throw new NotInGroupException();
       case 404: throw new GroupNotFoundException();
@@ -2921,15 +2929,20 @@ public class PushServiceSocket {
   };
 
   private static final ResponseCodeHandler GROUPS_V2_PATCH_RESPONSE_HANDLER = (responseCode, body, getHeader) -> {
+    if (getHeader.apply("X-Signal-Timestamp") == null) {
+      throw new NonSuccessfulResponseCodeException(500, "Missing timestamp header");
+    }
+
     if (responseCode == 400) throw new GroupPatchNotAcceptedException();
   };
 
-  private static final ResponseCodeHandler GROUPS_V2_GET_JOIN_INFO_HANDLER  = new ResponseCodeHandler() {
-    @Override
-    public void handle(int responseCode, ResponseBody body, Function<String, String> getHeader) throws NonSuccessfulResponseCodeException {
-      if (responseCode == 403) {
-        throw new ForbiddenException(Optional.ofNullable(getHeader.apply("X-Signal-Forbidden-Reason")));
-      }
+  private static final ResponseCodeHandler GROUPS_V2_GET_JOIN_INFO_HANDLER  = (responseCode, body, getHeader) -> {
+    if (getHeader.apply("X-Signal-Timestamp") == null) {
+      throw new NonSuccessfulResponseCodeException(500, "Missing timestamp header");
+    }
+
+    if (responseCode == 403) {
+      throw new ForbiddenException(Optional.ofNullable(getHeader.apply("X-Signal-Forbidden-Reason")));
     }
   };