diff --git a/src/main/java/com/google/devtools/build/lib/query2/PostAnalysisQueryEnvironment.java b/src/main/java/com/google/devtools/build/lib/query2/PostAnalysisQueryEnvironment.java
index 87cd767f644282..868690a1ba99ed 100644
--- a/src/main/java/com/google/devtools/build/lib/query2/PostAnalysisQueryEnvironment.java
+++ b/src/main/java/com/google/devtools/build/lib/query2/PostAnalysisQueryEnvironment.java
@@ -149,7 +149,7 @@ public QueryEvalResult evaluateQuery(
       QueryExpression expr, ThreadSafeOutputFormatterCallback<T> callback)
       throws QueryException, InterruptedException, IOException {
     beforeEvaluateQuery();
-    return super.evaluateQuery(expr, callback);
+    return evaluateQueryInternal(expr, callback);
   }
 
   private void beforeEvaluateQuery() throws QueryException {
diff --git a/src/main/java/com/google/devtools/build/lib/query2/SkyQueryEnvironment.java b/src/main/java/com/google/devtools/build/lib/query2/SkyQueryEnvironment.java
index 88064577df4982..fc0fee6ce2e8d2 100644
--- a/src/main/java/com/google/devtools/build/lib/query2/SkyQueryEnvironment.java
+++ b/src/main/java/com/google/devtools/build/lib/query2/SkyQueryEnvironment.java
@@ -514,7 +514,7 @@ public QueryEvalResult evaluateQuery(
     BatchStreamedCallback batchCallback =
         new BatchStreamedCallback(
             callback, BATCH_CALLBACK_SIZE, createUniquifierForOuterBatchStreamedCallback(expr));
-    return super.evaluateQuery(expr, batchCallback);
+    return evaluateQueryInternal(expr, batchCallback);
   }
 
   Map<SkyKey, Collection<Target>> targetifyValues(Map<SkyKey, ? extends Iterable<SkyKey>> input)
@@ -1080,8 +1080,7 @@ public void buildTransitiveClosure(
   }
 
   @Override
-  protected void preloadOrThrow(QueryExpression caller, Collection<String> patterns)
-      throws QueryException, TargetParsingException {
+  protected final void preloadOrThrow(QueryExpression caller, Collection<String> patterns) {
     // SkyQueryEnvironment directly evaluates target patterns in #getTarget and similar methods
     // using its graph, which is prepopulated using the universeScope (see #beforeEvaluateQuery),
     // so no preloading of target patterns is necessary.
diff --git a/src/main/java/com/google/devtools/build/lib/query2/common/AbstractBlazeQueryEnvironment.java b/src/main/java/com/google/devtools/build/lib/query2/common/AbstractBlazeQueryEnvironment.java
index 751d0b75eb9145..aeaeca80b6cb95 100644
--- a/src/main/java/com/google/devtools/build/lib/query2/common/AbstractBlazeQueryEnvironment.java
+++ b/src/main/java/com/google/devtools/build/lib/query2/common/AbstractBlazeQueryEnvironment.java
@@ -15,6 +15,7 @@
 
 import static com.google.common.util.concurrent.MoreExecutors.directExecutor;
 import static java.util.concurrent.TimeUnit.MINUTES;
+import static java.util.concurrent.TimeUnit.SECONDS;
 
 import com.google.common.base.Function;
 import com.google.common.base.Preconditions;
@@ -73,6 +74,8 @@
  */
 public abstract class AbstractBlazeQueryEnvironment<T>
     implements QueryEnvironment<T>, AutoCloseable {
+  private static final GoogleLogger logger = GoogleLogger.forEnclosingClass();
+
   protected ErrorSensingEventHandler<DetailedExitCode> eventHandler;
   protected final boolean keepGoing;
   protected final boolean strictScope;
@@ -83,8 +86,6 @@ public abstract class AbstractBlazeQueryEnvironment<T>
   protected final Set<Setting> settings;
   protected final List<QueryFunction> extraFunctions;
 
-  private static final GoogleLogger logger = GoogleLogger.forEnclosingClass();
-
   protected AbstractBlazeQueryEnvironment(
       boolean keepGoing,
       boolean strictScope,
@@ -131,6 +132,10 @@ protected QueryExpressionContext<T> createEmptyContext() {
     return QueryExpressionContext.empty();
   }
 
+  public abstract QueryEvalResult evaluateQuery(
+      QueryExpression expr, ThreadSafeOutputFormatterCallback<T> callback)
+      throws QueryException, IOException, InterruptedException;
+
   /**
    * Evaluate the specified query expression in this environment, streaming results to the given
    * {@code callback}. {@code callback.start()} will be called before query evaluation and {@code
@@ -143,7 +148,7 @@ protected QueryExpressionContext<T> createEmptyContext() {
    * @throws QueryException if the evaluation failed and {@code --nokeep_going} was in effect
    * @throws IOException for output formatter failures from {@code callback}
    */
-  public QueryEvalResult evaluateQuery(
+  protected final QueryEvalResult evaluateQueryInternal(
       QueryExpression expr, ThreadSafeOutputFormatterCallback<T> callback)
       throws QueryException, InterruptedException, IOException {
     EmptinessSensingCallback<T> emptySensingCallback = new EmptinessSensingCallback<>(callback);
@@ -330,7 +335,7 @@ public QueryExpression transformParsedQuery(QueryExpression queryExpression) {
   }
 
   @Override
-  public void handleError(
+  public final void handleError(
       QueryExpression expression, String message, DetailedExitCode detailedExitCode)
       throws QueryException {
     if (!keepGoing) {
@@ -358,6 +363,7 @@ public Map<Label, Target> getTargets(Iterable<Label> labels)
       try {
         target = getTarget(label);
       } catch (TargetNotFoundException e) {
+        logger.atInfo().withCause(e).atMostEvery(1, SECONDS).log("Failure to load %s", label);
         continue;
       }
       resultBuilder.put(label, target);
diff --git a/src/main/java/com/google/devtools/build/lib/query2/query/BlazeQueryEnvironment.java b/src/main/java/com/google/devtools/build/lib/query2/query/BlazeQueryEnvironment.java
index 8fe671b4e36c55..3c22142b0ca94e 100644
--- a/src/main/java/com/google/devtools/build/lib/query2/query/BlazeQueryEnvironment.java
+++ b/src/main/java/com/google/devtools/build/lib/query2/query/BlazeQueryEnvironment.java
@@ -68,6 +68,9 @@
 
 /**
  * The environment of a Blaze query. Not thread-safe.
+ *
+ * <p>This environment is valid only for a single query, called via {@link #evaluateQuery}. Call
+ * only once!
  */
 public class BlazeQueryEnvironment extends AbstractBlazeQueryEnvironment<Target> {
   private static final int MAX_DEPTH_FULL_SCAN_LIMIT = 20;
@@ -84,6 +87,8 @@ public class BlazeQueryEnvironment extends AbstractBlazeQueryEnvironment<Target>
 
   private final BlazeTargetAccessor accessor = new BlazeTargetAccessor(this);
 
+  private boolean doneQuery;
+
   /**
    * Note that the correct operation of this class critically depends on the Reporter being a
    * singleton object, shared by all cooperating classes contributing to Query.
@@ -130,8 +135,9 @@ public DigraphQueryEvalResult<Target> evaluateQuery(
       QueryExpression expr,
       ThreadSafeOutputFormatterCallback<Target> callback)
           throws QueryException, InterruptedException, IOException {
-    resolvedTargetPatterns.clear();
-    QueryEvalResult queryEvalResult = super.evaluateQuery(expr, callback);
+    Preconditions.checkState(!doneQuery, "Can only use environment for one query: %s", expr);
+    doneQuery = true;
+    QueryEvalResult queryEvalResult = evaluateQueryInternal(expr, callback);
     return new DigraphQueryEvalResult<>(
         queryEvalResult.getSuccess(),
         queryEvalResult.isEmpty(),
@@ -458,13 +464,16 @@ public ThreadSafeMutableSet<Target> getBuildFiles(
   @Override
   protected void preloadOrThrow(QueryExpression caller, Collection<String> patterns)
       throws TargetParsingException, InterruptedException {
-    if (!resolvedTargetPatterns.keySet().containsAll(patterns)) {
-      // Note that this may throw a RuntimeException if deps are missing in Skyframe and this is
-      // being called from within a SkyFunction.
-      resolvedTargetPatterns.putAll(
-          targetPatternPreloader.preloadTargetPatterns(
-              eventHandler, relativeWorkingDirectory, patterns, keepGoing));
-    }
+    Preconditions.checkState(
+        resolvedTargetPatterns.isEmpty(),
+        "Already resolved patterns: %s %s",
+        patterns,
+        resolvedTargetPatterns);
+    // Note that this may throw a RuntimeException if deps are missing in Skyframe and this is
+    // being called from within a SkyFunction.
+    resolvedTargetPatterns.putAll(
+        targetPatternPreloader.preloadTargetPatterns(
+            eventHandler, relativeWorkingDirectory, patterns, keepGoing));
   }
 
   private static void addIfUniqueLabel(Node<Target> node, Set<Label> labels, Set<Target> nodes) {
diff --git a/src/main/java/com/google/devtools/build/lib/query2/query/GraphlessBlazeQueryEnvironment.java b/src/main/java/com/google/devtools/build/lib/query2/query/GraphlessBlazeQueryEnvironment.java
index 9a41bbad9c0f25..804aabfccbf2ca 100644
--- a/src/main/java/com/google/devtools/build/lib/query2/query/GraphlessBlazeQueryEnvironment.java
+++ b/src/main/java/com/google/devtools/build/lib/query2/query/GraphlessBlazeQueryEnvironment.java
@@ -13,6 +13,7 @@
 // limitations under the License.
 package com.google.devtools.build.lib.query2.query;
 
+import com.google.common.base.Preconditions;
 import com.google.common.collect.Sets;
 import com.google.devtools.build.lib.cmdline.Label;
 import com.google.devtools.build.lib.cmdline.PackageIdentifier;
@@ -36,6 +37,7 @@
 import com.google.devtools.build.lib.query2.engine.Callback;
 import com.google.devtools.build.lib.query2.engine.MinDepthUniquifier;
 import com.google.devtools.build.lib.query2.engine.QueryEnvironment.CustomFunctionQueryEnvironment;
+import com.google.devtools.build.lib.query2.engine.QueryEvalResult;
 import com.google.devtools.build.lib.query2.engine.QueryException;
 import com.google.devtools.build.lib.query2.engine.QueryExpression;
 import com.google.devtools.build.lib.query2.engine.QueryExpressionContext;
@@ -44,8 +46,10 @@
 import com.google.devtools.build.lib.query2.engine.QueryUtil.ThreadSafeMutableKeyExtractorBackedSetImpl;
 import com.google.devtools.build.lib.query2.engine.QueryUtil.UniquifierImpl;
 import com.google.devtools.build.lib.query2.engine.SkyframeRestartQueryException;
+import com.google.devtools.build.lib.query2.engine.ThreadSafeOutputFormatterCallback;
 import com.google.devtools.build.lib.query2.engine.Uniquifier;
 import com.google.devtools.build.lib.vfs.PathFragment;
+import java.io.IOException;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.HashMap;
@@ -67,6 +71,9 @@
  * com.google.devtools.build.lib.query2.engine.DigraphQueryEvalResult}, and can therefore not be
  * used with most existing {@link com.google.devtools.build.lib.query2.query.output.OutputFormatter}
  * implementations, many of which expect the latter.
+ *
+ * <p>This environment is valid only for a single query, called via {@link #evaluateQuery}. Call
+ * only once!
  */
 public class GraphlessBlazeQueryEnvironment extends AbstractBlazeQueryEnvironment<Target>
     implements CustomFunctionQueryEnvironment<Target> {
@@ -83,6 +90,8 @@ public class GraphlessBlazeQueryEnvironment extends AbstractBlazeQueryEnvironmen
 
   private final BlazeTargetAccessor accessor = new BlazeTargetAccessor(this);
 
+  private boolean doneQuery = false;
+
   /**
    * Note that the correct operation of this class critically depends on the Reporter being a
    * singleton object, shared by all cooperating classes contributing to Query.
@@ -144,6 +153,15 @@ public QueryTaskFuture<Void> eval(
     return expr.eval(this, context, callback);
   }
 
+  @Override
+  public QueryEvalResult evaluateQuery(
+      QueryExpression expr, ThreadSafeOutputFormatterCallback<Target> callback)
+      throws QueryException, IOException, InterruptedException {
+    Preconditions.checkState(!doneQuery, "Can only use environment for one query: %s", expr);
+    doneQuery = true;
+    return evaluateQueryInternal(expr, callback);
+  }
+
   @Override
   public void close() {
     // BlazeQueryEnvironment has no resources that need to be cleaned up.
@@ -457,13 +475,16 @@ public ThreadSafeMutableSet<Target> getBuildFiles(
   @Override
   protected void preloadOrThrow(QueryExpression caller, Collection<String> patterns)
       throws TargetParsingException, InterruptedException {
-    if (!resolvedTargetPatterns.keySet().containsAll(patterns)) {
-      // Note that this may throw a RuntimeException if deps are missing in Skyframe and this is
-      // being called from within a SkyFunction.
-      resolvedTargetPatterns.putAll(
-          targetPatternPreloader.preloadTargetPatterns(
-              eventHandler, relativeWorkingDirectory, patterns, keepGoing));
-    }
+    Preconditions.checkState(
+        resolvedTargetPatterns.isEmpty(),
+        "Already resolved patterns: %s %s",
+        patterns,
+        resolvedTargetPatterns);
+    // Note that this may throw a RuntimeException if deps are missing in Skyframe and this is
+    // being called from within a SkyFunction.
+    resolvedTargetPatterns.putAll(
+        targetPatternPreloader.preloadTargetPatterns(
+            eventHandler, relativeWorkingDirectory, patterns, keepGoing));
   }
 
   @Override