diff --git a/src/main/java/org/schabi/newpipe/extractor/services/soundcloud/SoundcloudStreamExtractor.java b/src/main/java/org/schabi/newpipe/extractor/services/soundcloud/SoundcloudStreamExtractor.java
index c4a42414..d323a262 100644
--- a/src/main/java/org/schabi/newpipe/extractor/services/soundcloud/SoundcloudStreamExtractor.java
+++ b/src/main/java/org/schabi/newpipe/extractor/services/soundcloud/SoundcloudStreamExtractor.java
@@ -7,12 +7,13 @@ import org.schabi.newpipe.extractor.*;
 import org.schabi.newpipe.extractor.exceptions.ContentNotAvailableException;
 import org.schabi.newpipe.extractor.exceptions.ExtractionException;
 import org.schabi.newpipe.extractor.exceptions.ParsingException;
-import org.schabi.newpipe.extractor.exceptions.ReCaptchaException;
 import org.schabi.newpipe.extractor.stream.*;
-import org.schabi.newpipe.extractor.utils.Parser;
 
 import javax.annotation.Nonnull;
+import javax.annotation.Nullable;
 import java.io.IOException;
+import java.io.UnsupportedEncodingException;
+import java.net.URLEncoder;
 import java.util.*;
 
 public class SoundcloudStreamExtractor extends StreamExtractor {
@@ -127,8 +128,8 @@ public class SoundcloudStreamExtractor extends StreamExtractor {
         List<AudioStream> audioStreams = new ArrayList<>();
         Downloader dl = NewPipe.getDownloader();
 
-        String apiUrl = "https://api.soundcloud.com/i1/tracks/" + getId() + "/streams"
-                + "?client_id=" + SoundcloudParsingHelper.clientId();
+        String apiUrl = "https://api.soundcloud.com/i1/tracks/" + urlEncode(getId()) + "/streams"
+                + "?client_id=" + urlEncode(SoundcloudParsingHelper.clientId());
 
         String response = dl.download(apiUrl);
         JsonObject responseObject;
@@ -148,6 +149,14 @@ public class SoundcloudStreamExtractor extends StreamExtractor {
         return audioStreams;
     }
 
+    private static String urlEncode(String value) {
+        try {
+            return URLEncoder.encode(value, "UTF-8");
+        } catch (UnsupportedEncodingException e) {
+            throw new IllegalStateException(e);
+        }
+    }
+
     @Override
     public List<VideoStream> getVideoStreams() throws IOException, ExtractionException {
         return null;
@@ -159,11 +168,13 @@ public class SoundcloudStreamExtractor extends StreamExtractor {
     }
 
     @Override
+    @Nullable
     public List<Subtitles> getSubtitlesDefault() throws IOException, ExtractionException {
         return null;
     }
 
     @Override
+    @Nullable
     public List<Subtitles> getSubtitles(SubtitlesFormat format) throws IOException, ExtractionException {
         return null;
     }
@@ -182,8 +193,8 @@ public class SoundcloudStreamExtractor extends StreamExtractor {
     public StreamInfoItemCollector getRelatedVideos() throws IOException, ExtractionException {
         StreamInfoItemCollector collector = new StreamInfoItemCollector(getServiceId());
 
-        String apiUrl = "https://api-v2.soundcloud.com/tracks/" + getId() + "/related"
-                + "?client_id=" + SoundcloudParsingHelper.clientId();
+        String apiUrl = "https://api-v2.soundcloud.com/tracks/" + urlEncode(getId()) + "/related"
+                + "?client_id=" + urlEncode(SoundcloudParsingHelper.clientId());
 
         SoundcloudParsingHelper.getStreamsFromApi(collector, apiUrl);
         return collector;
diff --git a/src/main/java/org/schabi/newpipe/extractor/services/youtube/YoutubeStreamExtractor.java b/src/main/java/org/schabi/newpipe/extractor/services/youtube/YoutubeStreamExtractor.java
index c7e96a2f..0f93508e 100644
--- a/src/main/java/org/schabi/newpipe/extractor/services/youtube/YoutubeStreamExtractor.java
+++ b/src/main/java/org/schabi/newpipe/extractor/services/youtube/YoutubeStreamExtractor.java
@@ -403,11 +403,13 @@ public class YoutubeStreamExtractor extends StreamExtractor {
     }
 
     @Override
+    @Nullable
     public List<Subtitles> getSubtitlesDefault() throws IOException, ExtractionException {
         return getSubtitles(SubtitlesFormat.TTML);
     }
 
     @Override
+    @Nullable
     public List<Subtitles> getSubtitles(SubtitlesFormat format) throws IOException, ExtractionException {
         JsonObject playerConfig = getPlayerConfig(getPageHtml());
         String playerResponse = playerConfig.getObject("args").getString("player_response");
diff --git a/src/main/java/org/schabi/newpipe/extractor/stream/StreamExtractor.java b/src/main/java/org/schabi/newpipe/extractor/stream/StreamExtractor.java
index f77fcbc8..61df951f 100644
--- a/src/main/java/org/schabi/newpipe/extractor/stream/StreamExtractor.java
+++ b/src/main/java/org/schabi/newpipe/extractor/stream/StreamExtractor.java
@@ -20,17 +20,16 @@ package org.schabi.newpipe.extractor.stream;
  * along with NewPipe.  If not, see <http://www.gnu.org/licenses/>.
  */
 
-import com.grack.nanojson.JsonParserException;
 import org.schabi.newpipe.extractor.Extractor;
 import org.schabi.newpipe.extractor.StreamingService;
 import org.schabi.newpipe.extractor.Subtitles;
 import org.schabi.newpipe.extractor.UrlIdHandler;
 import org.schabi.newpipe.extractor.exceptions.ExtractionException;
 import org.schabi.newpipe.extractor.exceptions.ParsingException;
-import org.schabi.newpipe.extractor.exceptions.ReCaptchaException;
 import org.schabi.newpipe.extractor.utils.Parser;
 
 import javax.annotation.Nonnull;
+import javax.annotation.Nullable;
 import java.io.IOException;
 import java.util.List;
 
@@ -57,6 +56,12 @@ public abstract class StreamExtractor extends Extractor {
     public abstract String getThumbnailUrl() throws ParsingException;
     @Nonnull
     public abstract String getDescription() throws ParsingException;
+
+    /**
+     * Get the age limit
+     * @return The age which limits the content or {@value NO_AGE_LIMIT} if there is no limit
+     * @throws ParsingException if an error occurs while parsing
+     */
     public abstract int getAgeLimit() throws ParsingException;
 
     public abstract long getLength() throws ParsingException;
@@ -126,7 +131,11 @@ public abstract class StreamExtractor extends Extractor {
     public abstract List<AudioStream> getAudioStreams() throws IOException, ExtractionException;
     public abstract List<VideoStream> getVideoStreams() throws IOException, ExtractionException;
     public abstract List<VideoStream> getVideoOnlyStreams() throws IOException, ExtractionException;
+
+    @Nullable
     public abstract List<Subtitles> getSubtitlesDefault() throws IOException, ExtractionException;
+
+    @Nullable
     public abstract List<Subtitles> getSubtitles(SubtitlesFormat format) throws IOException, ExtractionException;
 
     public abstract StreamType getStreamType() throws ParsingException;
diff --git a/src/test/java/org/schabi/newpipe/extractor/services/youtube/YoutubeStreamExtractorRestrictedTest.java b/src/test/java/org/schabi/newpipe/extractor/services/youtube/YoutubeStreamExtractorRestrictedTest.java
index f914519a..1c362d5d 100644
--- a/src/test/java/org/schabi/newpipe/extractor/services/youtube/YoutubeStreamExtractorRestrictedTest.java
+++ b/src/test/java/org/schabi/newpipe/extractor/services/youtube/YoutubeStreamExtractorRestrictedTest.java
@@ -116,12 +116,12 @@ public class YoutubeStreamExtractorRestrictedTest {
     @Test
     public void testGetSubtitlesListDefault() throws IOException, ExtractionException {
         // Video (/view?v=YQHsXMglC9A) set in the setUp() method has no captions => null
-        assertTrue(extractor.getSubtitlesDefault() == null);
+        assertNull(extractor.getSubtitlesDefault());
     }
 
     @Test
     public void testGetSubtitlesList() throws IOException, ExtractionException {
         // Video (/view?v=YQHsXMglC9A) set in the setUp() method has no captions => null
-        assertTrue(extractor.getSubtitles(SubtitlesFormat.VTT) == null);
+        assertNull(extractor.getSubtitles(SubtitlesFormat.VTT));
     }
 }