diff --git a/sdks/java/expansion-service/src/main/java/org/apache/beam/sdk/expansion/service/ExpansionServiceSchemaTransformProvider.java b/sdks/java/expansion-service/src/main/java/org/apache/beam/sdk/expansion/service/ExpansionServiceSchemaTransformProvider.java
index 406e72c751db..4a8a467bb49a 100644
--- a/sdks/java/expansion-service/src/main/java/org/apache/beam/sdk/expansion/service/ExpansionServiceSchemaTransformProvider.java
+++ b/sdks/java/expansion-service/src/main/java/org/apache/beam/sdk/expansion/service/ExpansionServiceSchemaTransformProvider.java
@@ -41,6 +41,7 @@
 import org.apache.beam.sdk.values.Row;
 import org.apache.beam.sdk.values.TupleTag;
 import org.apache.beam.vendor.grpc.v1p48p1.com.google.protobuf.InvalidProtocolBufferException;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 @SuppressWarnings({"rawtypes"})
 public class ExpansionServiceSchemaTransformProvider implements TransformProvider {
@@ -49,9 +50,9 @@ public class ExpansionServiceSchemaTransformProvider implements TransformProvide
 
   private Map<String, org.apache.beam.sdk.schemas.transforms.SchemaTransformProvider>
       schemaTransformProviders = new HashMap<>();
-  private static ExpansionServiceSchemaTransformProvider transformProvider = null;
+  private static @Nullable ExpansionServiceSchemaTransformProvider transformProvider = null;
 
-  private void loadSchemaTransforms() {
+  private ExpansionServiceSchemaTransformProvider() {
     try {
       for (org.apache.beam.sdk.schemas.transforms.SchemaTransformProvider schemaTransformProvider :
           ServiceLoader.load(
@@ -68,10 +69,6 @@ private void loadSchemaTransforms() {
     }
   }
 
-  private ExpansionServiceSchemaTransformProvider() {
-    loadSchemaTransforms();
-  }
-
   public static ExpansionServiceSchemaTransformProvider of() {
     if (transformProvider == null) {
       transformProvider = new ExpansionServiceSchemaTransformProvider();
@@ -142,6 +139,10 @@ public PTransform getTransform(FunctionSpec spec) {
     String identifier = payload.getIdentifier();
     org.apache.beam.sdk.schemas.transforms.SchemaTransformProvider provider =
         schemaTransformProviders.get(identifier);
+    if (provider == null) {
+      throw new IllegalArgumentException(
+          "Could not find a SchemaTransform with identifier " + identifier);
+    }
 
     Schema configSchemaFromRequest =
         SchemaTranslation.schemaFromProto((payload.getConfigurationSchema()));