diff --git a/api/src/org/labkey/api/dataiterator/SimpleTranslator.java b/api/src/org/labkey/api/dataiterator/SimpleTranslator.java
index 46641fde588..a015956b15c 100644
--- a/api/src/org/labkey/api/dataiterator/SimpleTranslator.java
+++ b/api/src/org/labkey/api/dataiterator/SimpleTranslator.java
@@ -121,7 +121,6 @@
  */
 public class SimpleTranslator extends AbstractDataIterator implements DataIterator, ScrollableDataIterator
 {
-    public static final String DEPRECATED_NULL_MISSING_VALUE_RESOLUTION = "deprecatedNullMissingValueResolution";
     private static final Logger LOG = LogManager.getLogger(SimpleTranslator.class);
 
     /**
@@ -1354,17 +1353,7 @@ private SimpleConvertColumn createConvertColumn(@NotNull ColumnInfo col, int fro
         {
             RemapMissingBehavior missing = remapMissingBehavior;
             if (missing == null)
-            {
-                if (OptionalFeatureService.get().isFeatureEnabled(DEPRECATED_NULL_MISSING_VALUE_RESOLUTION))
-                {
-                    // Issue 48347: if the lookup field has a "Lookup Validator", then treat the missing values as an error
-                    boolean hasValidator = pd != null && pd.getValidators().stream().anyMatch(v -> PropertyValidatorType.Lookup.getLabel().equalsIgnoreCase(v.getName()));
-
-                    missing = col.isRequired() || hasValidator ? RemapMissingBehavior.Error : RemapMissingBehavior.Null;
-                }
-                else
-                    missing = RemapMissingBehavior.Error;
-            }
+                missing = RemapMissingBehavior.Error;
             c = new RemappingConvertColumn(c, fromIndex, col, missing, true, lookupResolutionType);
         }
 
diff --git a/core/src/org/labkey/core/CoreModule.java b/core/src/org/labkey/core/CoreModule.java
index e34f0060987..3dd84bbad36 100644
--- a/core/src/org/labkey/core/CoreModule.java
+++ b/core/src/org/labkey/core/CoreModule.java
@@ -87,7 +87,6 @@
 import org.labkey.api.data.dialect.SqlDialectManager;
 import org.labkey.api.data.dialect.SqlDialectRegistry;
 import org.labkey.api.data.statistics.StatsService;
-import org.labkey.api.dataiterator.SimpleTranslator;
 import org.labkey.api.exp.property.PropertyService;
 import org.labkey.api.exp.property.TestDomainKind;
 import org.labkey.api.external.tools.ExternalToolsViewService;
@@ -542,10 +541,6 @@ public QuerySchema createSchema(DefaultSchema schema, Module module)
             "Short-circuit robots",
             "Save resources by not rendering pages marked as 'noindex' for robots. This is experimental as not all robots are search engines.",
             false);
-        OptionalFeatureService.get().addFeatureFlag(new OptionalFeatureFlag(SimpleTranslator.DEPRECATED_NULL_MISSING_VALUE_RESOLUTION,
-            "Resolve Missing Lookup Values to Null",
-            "When Lookup Validation for a field is not selected and lookup by alternate key is enabled, resolves missing lookup values to null instead of throwing an error. This option will be removed in LabKey Server v25.11.",
-            false, false, OptionalFeatureService.FeatureType.Deprecated));
         OptionalFeatureService.get().addFeatureFlag(new OptionalFeatureFlag(TabLoader.FEATUREFLAG_UNESCAPE_BACKSLASH,
             "Unescape backslash character on import",
             "Treat backslash '\\' character as an escape character when loading data from file.",