diff --git a/portability-transfer/src/main/java/org/datatransferproject/transfer/copier/PortabilityAbstractInMemoryDataCopier.java b/portability-transfer/src/main/java/org/datatransferproject/transfer/copier/PortabilityAbstractInMemoryDataCopier.java
index 9709e3a3a..1d3074405 100644
--- a/portability-transfer/src/main/java/org/datatransferproject/transfer/copier/PortabilityAbstractInMemoryDataCopier.java
+++ b/portability-transfer/src/main/java/org/datatransferproject/transfer/copier/PortabilityAbstractInMemoryDataCopier.java
@@ -16,6 +16,7 @@
 package org.datatransferproject.transfer.copier;
 
 import com.google.cloud.datastore.DatastoreException;
+import static com.google.common.base.Preconditions.checkNotNull;
 import com.google.common.base.Stopwatch;
 import com.google.inject.Provider;
 import java.io.IOException;
@@ -125,6 +126,7 @@ protected ExportResult<?> copyIteration(
     DataModel exportedData = exportResult.getExportedData();
     if (exportedData != null) {
       PortabilityJob job = jobStore.findJob(jobId);
+      checkNotNull(job, "Transfer job not found from jobStore, mid-way through copy iteration, for the job ID \"%s\"", jobId.toString());
       TransferMode transferMode =
           job.transferMode() == null ? TransferMode.DATA_TRANSFER : job.transferMode();
       switch (transferMode) {