diff --git a/library/common/src/main/java/com/google/android/exoplayer2/MediaItem.java b/library/common/src/main/java/com/google/android/exoplayer2/MediaItem.java
index 678822b7d2..14c1d6d1e7 100644
--- a/library/common/src/main/java/com/google/android/exoplayer2/MediaItem.java
+++ b/library/common/src/main/java/com/google/android/exoplayer2/MediaItem.java
@@ -231,7 +231,7 @@ public final class MediaItem {
     }
 
     /**
-     * Sets the optional DRM license server URI. If this URI is set, the {@link
+     * Sets the optional default DRM license server URI. If this URI is set, the {@link
      * DrmConfiguration#uuid} needs to be specified as well.
      *
      * <p>If {@link #setUri} is passed a non-null {@code uri}, the DRM license server URI is used to
@@ -243,7 +243,7 @@ public final class MediaItem {
     }
 
     /**
-     * Sets the optional DRM license server URI. If this URI is set, the {@link
+     * Sets the optional default DRM license server URI. If this URI is set, the {@link
      * DrmConfiguration#uuid} needs to be specified as well.
      *
      * <p>If {@link #setUri} is passed a non-null {@code uri}, the DRM license server URI is used to
@@ -294,8 +294,8 @@ public final class MediaItem {
     }
 
     /**
-     * Sets whether to use the DRM license server URI of the media item for key requests that
-     * include their own DRM license server URI.
+     * Sets whether to force use the default DRM license server URI even if the media specifies its
+     * own DRM license server URI.
      *
      * <p>If {@link #setUri} is passed a non-null {@code uri}, the DRM force default license flag is
      * used to create a {@link PlaybackProperties} object. Otherwise it will be ignored.
@@ -568,8 +568,8 @@ public final class MediaItem {
     public final UUID uuid;
 
     /**
-     * Optional DRM license server {@link Uri}. If {@code null} then the DRM license server must be
-     * specified by the media.
+     * Optional default DRM license server {@link Uri}. If {@code null} then the DRM license server
+     * must be specified by the media.
      */
     @Nullable public final Uri licenseUri;
 
@@ -586,8 +586,8 @@ public final class MediaItem {
     public final boolean playClearContentWithoutKey;
 
     /**
-     * Sets whether to use the DRM license server URI of the media item for key requests that
-     * include their own DRM license server URI.
+     * Whether to force use of {@link #licenseUri} even if the media specifies its own DRM license
+     * server URI.
      */
     public final boolean forceDefaultLicenseUri;
 
@@ -605,6 +605,7 @@ public final class MediaItem {
         boolean playClearContentWithoutKey,
         List<Integer> drmSessionForClearTypes,
         @Nullable byte[] keySetId) {
+      Assertions.checkArgument(!(forceDefaultLicenseUri && licenseUri == null));
       this.uuid = uuid;
       this.licenseUri = licenseUri;
       this.requestHeaders = requestHeaders;
diff --git a/library/core/src/main/java/com/google/android/exoplayer2/drm/HttpMediaDrmCallback.java b/library/core/src/main/java/com/google/android/exoplayer2/drm/HttpMediaDrmCallback.java
index 7ab90b023e..6a20cf7bda 100644
--- a/library/core/src/main/java/com/google/android/exoplayer2/drm/HttpMediaDrmCallback.java
+++ b/library/core/src/main/java/com/google/android/exoplayer2/drm/HttpMediaDrmCallback.java
@@ -15,6 +15,7 @@
  */
 package com.google.android.exoplayer2.drm;
 
+import android.net.Uri;
 import android.text.TextUtils;
 import androidx.annotation.Nullable;
 import com.google.android.exoplayer2.C;
@@ -27,6 +28,7 @@ import com.google.android.exoplayer2.upstream.HttpDataSource.InvalidResponseCode
 import com.google.android.exoplayer2.upstream.StatsDataSource;
 import com.google.android.exoplayer2.util.Assertions;
 import com.google.android.exoplayer2.util.Util;
+import com.google.common.collect.ImmutableMap;
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.List;
@@ -39,29 +41,35 @@ public final class HttpMediaDrmCallback implements MediaDrmCallback {
   private static final int MAX_MANUAL_REDIRECTS = 5;
 
   private final HttpDataSource.Factory dataSourceFactory;
-  private final String defaultLicenseUrl;
+  @Nullable private final String defaultLicenseUrl;
   private final boolean forceDefaultLicenseUrl;
   private final Map<String, String> keyRequestProperties;
 
   /**
    * @param defaultLicenseUrl The default license URL. Used for key requests that do not specify
-   *     their own license URL.
+   *     their own license URL. May be {@code null} if it's known that all key requests will specify
+   *     their own URLs.
    * @param dataSourceFactory A factory from which to obtain {@link HttpDataSource} instances.
    */
-  public HttpMediaDrmCallback(String defaultLicenseUrl, HttpDataSource.Factory dataSourceFactory) {
+  public HttpMediaDrmCallback(
+      @Nullable String defaultLicenseUrl, HttpDataSource.Factory dataSourceFactory) {
     this(defaultLicenseUrl, /* forceDefaultLicenseUrl= */ false, dataSourceFactory);
   }
 
   /**
    * @param defaultLicenseUrl The default license URL. Used for key requests that do not specify
-   *     their own license URL, or for all key requests if {@code forceDefaultLicenseUrl} is
-   *     set to true.
-   * @param forceDefaultLicenseUrl Whether to use {@code defaultLicenseUrl} for key requests that
-   *     include their own license URL.
+   *     their own license URL, or for all key requests if {@code forceDefaultLicenseUrl} is set to
+   *     true. May be {@code null} if {@code forceDefaultLicenseUrl} is {@code false} and if it's
+   *     known that all key requests will specify their own URLs.
+   * @param forceDefaultLicenseUrl Whether to force use of {@code defaultLicenseUrl} for key
+   *     requests that include their own license URL.
    * @param dataSourceFactory A factory from which to obtain {@link HttpDataSource} instances.
    */
-  public HttpMediaDrmCallback(String defaultLicenseUrl, boolean forceDefaultLicenseUrl,
+  public HttpMediaDrmCallback(
+      @Nullable String defaultLicenseUrl,
+      boolean forceDefaultLicenseUrl,
       HttpDataSource.Factory dataSourceFactory) {
+    Assertions.checkArgument(!(forceDefaultLicenseUrl && TextUtils.isEmpty(defaultLicenseUrl)));
     this.dataSourceFactory = dataSourceFactory;
     this.defaultLicenseUrl = defaultLicenseUrl;
     this.forceDefaultLicenseUrl = forceDefaultLicenseUrl;
@@ -121,6 +129,14 @@ public final class HttpMediaDrmCallback implements MediaDrmCallback {
     if (forceDefaultLicenseUrl || TextUtils.isEmpty(url)) {
       url = defaultLicenseUrl;
     }
+    if (TextUtils.isEmpty(url)) {
+      throw new MediaDrmCallbackException(
+          new DataSpec.Builder().setUri(Uri.EMPTY).build(),
+          Uri.EMPTY,
+          /* responseHeaders= */ ImmutableMap.of(),
+          /* bytesLoaded= */ 0,
+          /* cause= */ new IllegalStateException("No license URL"));
+    }
     Map<String, String> requestProperties = new HashMap<>();
     // Add standard request properties for supported schemes.
     String contentType = C.PLAYREADY_UUID.equals(uuid) ? "text/xml"
diff --git a/library/core/src/main/java/com/google/android/exoplayer2/source/MediaSourceDrmHelper.java b/library/core/src/main/java/com/google/android/exoplayer2/source/MediaSourceDrmHelper.java
index 7859254401..f4a7b89fc7 100644
--- a/library/core/src/main/java/com/google/android/exoplayer2/source/MediaSourceDrmHelper.java
+++ b/library/core/src/main/java/com/google/android/exoplayer2/source/MediaSourceDrmHelper.java
@@ -17,7 +17,6 @@ package com.google.android.exoplayer2.source;
 
 import static com.google.android.exoplayer2.ExoPlayerLibraryInfo.DEFAULT_USER_AGENT;
 import static com.google.android.exoplayer2.drm.DefaultDrmSessionManager.MODE_PLAYBACK;
-import static com.google.android.exoplayer2.util.Util.castNonNull;
 
 import androidx.annotation.Nullable;
 import com.google.android.exoplayer2.MediaItem;
@@ -68,7 +67,7 @@ public final class MediaSourceDrmHelper {
     Assertions.checkNotNull(mediaItem.playbackProperties);
     @Nullable
     MediaItem.DrmConfiguration drmConfiguration = mediaItem.playbackProperties.drmConfiguration;
-    if (drmConfiguration == null || drmConfiguration.licenseUri == null || Util.SDK_INT < 18) {
+    if (drmConfiguration == null || Util.SDK_INT < 18) {
       return DrmSessionManager.getDummyDrmSessionManager();
     }
     HttpDataSource.Factory dataSourceFactory =
@@ -77,7 +76,7 @@ public final class MediaSourceDrmHelper {
             : new DefaultHttpDataSourceFactory(userAgent != null ? userAgent : DEFAULT_USER_AGENT);
     HttpMediaDrmCallback httpDrmCallback =
         new HttpMediaDrmCallback(
-            castNonNull(drmConfiguration.licenseUri).toString(),
+            drmConfiguration.licenseUri == null ? null : drmConfiguration.licenseUri.toString(),
             drmConfiguration.forceDefaultLicenseUri,
             dataSourceFactory);
     for (Map.Entry<String, String> entry : drmConfiguration.requestHeaders.entrySet()) {