diff --git a/src/SIL.Machine.AspNetCore/Services/ClearMLService.cs b/src/SIL.Machine.AspNetCore/Services/ClearMLService.cs
index 2805e9612..b7022dd6b 100644
--- a/src/SIL.Machine.AspNetCore/Services/ClearMLService.cs
+++ b/src/SIL.Machine.AspNetCore/Services/ClearMLService.cs
@@ -97,7 +97,7 @@ public async Task<string> CreateTaskAsync(
             + $"    'trg_lang': '{ConvertLanguageTag(targetLanguageTag)}',\n"
             + $"    'max_steps': {_options.CurrentValue.MaxSteps},\n"
             + $"    'shared_file_uri': '{sharedFileUri}',\n"
-            + $"    'clearml': True\n"
+            + $"    'clearml': True,\n"
             + "}\n"
             + "run(args)\n";
 
diff --git a/src/SIL.Machine.AspNetCore/Services/SmtTransferEngineBuildJob.cs b/src/SIL.Machine.AspNetCore/Services/SmtTransferEngineBuildJob.cs
index 5edc3ac57..6ad7ab411 100644
--- a/src/SIL.Machine.AspNetCore/Services/SmtTransferEngineBuildJob.cs
+++ b/src/SIL.Machine.AspNetCore/Services/SmtTransferEngineBuildJob.cs
@@ -43,7 +43,6 @@ CancellationToken cancellationToken
     )
     {
         IDistributedReaderWriterLock rwLock = await _lockFactory.CreateAsync(engineId, cancellationToken);
-
         var tokenizer = new LatinWordTokenizer();
         var detokenizer = new LatinWordDetokenizer();
         ITrainer? smtModelTrainer = null;
diff --git a/src/SIL.Machine/Corpora/CorpusAlignmentException.cs b/src/SIL.Machine/Corpora/CorpusAlignmentException.cs
new file mode 100644
index 000000000..c86dd8cfd
--- /dev/null
+++ b/src/SIL.Machine/Corpora/CorpusAlignmentException.cs
@@ -0,0 +1,12 @@
+using System;
+
+namespace SIL.Machine.Corpora
+{
+    public class CorpusAlignmentException : Exception
+    {
+        public CorpusAlignmentException(string sourceRef, string targetRef)
+            : base(
+                $"Invalid format in {sourceRef} and {targetRef}. Mismatched key formats \"{sourceRef}\" and \"{targetRef}\". There may be an extraneous tab, missing ref, or inconsistent use of user-defined refs."
+            ) { }
+    }
+}
diff --git a/src/SIL.Machine/Corpora/ParallelTextCorpus.cs b/src/SIL.Machine/Corpora/ParallelTextCorpus.cs
index ac743933a..31baf1b79 100644
--- a/src/SIL.Machine/Corpora/ParallelTextCorpus.cs
+++ b/src/SIL.Machine/Corpora/ParallelTextCorpus.cs
@@ -94,7 +94,18 @@ public IEnumerable<ParallelTextRow> GetRows()
                 bool trgCompleted = !trgEnumerator.MoveNext();
                 while (!srcCompleted && !trgCompleted)
                 {
-                    int compare1 = RowRefComparer.Compare(srcEnumerator.Current.Ref, trgEnumerator.Current.Ref);
+                    int compare1 = 0;
+                    try
+                    {
+                        compare1 = RowRefComparer.Compare(srcEnumerator.Current.Ref, trgEnumerator.Current.Ref);
+                    }
+                    catch (ArgumentException)
+                    {
+                        throw new CorpusAlignmentException(
+                            srcEnumerator.Current.Ref.ToString(),
+                            trgEnumerator.Current.Ref.ToString()
+                        );
+                    }
                     if (compare1 < 0)
                     {
                         if (!AllTargetRows && srcEnumerator.Current.IsInRange)
@@ -176,9 +187,19 @@ ParallelTextRow row in CreateTargetRows(
                         int compare2;
                         do
                         {
-                            compare2 = alignmentEnumerator.MoveNext()
-                                ? RowRefComparer.Compare(srcEnumerator.Current.Ref, alignmentEnumerator.Current.Ref)
-                                : 1;
+                            try
+                            {
+                                compare2 = alignmentEnumerator.MoveNext()
+                                    ? RowRefComparer.Compare(srcEnumerator.Current.Ref, alignmentEnumerator.Current.Ref)
+                                    : 1;
+                            }
+                            catch (ArgumentException)
+                            {
+                                throw new CorpusAlignmentException(
+                                    srcEnumerator.Current.Ref.ToString(),
+                                    trgEnumerator.Current.Ref.ToString()
+                                );
+                            }
                         } while (compare2 < 0);
 
                         if (
@@ -378,9 +399,15 @@ private IEnumerable<ParallelTextRow> CreateRows(
 
         private bool CheckSameRefRows(List<TextRow> sameRefRows, TextRow otherRow)
         {
-            if (sameRefRows.Count > 0 && RowRefComparer.Compare(sameRefRows[0].Ref, otherRow.Ref) != 0)
-                sameRefRows.Clear();
-
+            try
+            {
+                if (sameRefRows.Count > 0 && RowRefComparer.Compare(sameRefRows[0].Ref, otherRow.Ref) != 0)
+                    sameRefRows.Clear();
+            }
+            catch (ArgumentException)
+            {
+                throw new CorpusAlignmentException(sameRefRows[0].Ref.ToString(), otherRow.Ref.ToString());
+            }
             return sameRefRows.Count > 0;
         }