diff --git a/src/main/java/me/kavin/piped/utils/ResponseHelper.java b/src/main/java/me/kavin/piped/utils/ResponseHelper.java
index 5dcc562..b31bc3a 100644
--- a/src/main/java/me/kavin/piped/utils/ResponseHelper.java
+++ b/src/main/java/me/kavin/piped/utils/ResponseHelper.java
@@ -274,6 +274,9 @@ public class ResponseHelper {
     public static byte[] channelPageResponse(String channelId, String prevpageStr)
             throws IOException, ExtractionException {
 
+        if (StringUtils.isEmpty(prevpageStr))
+            return mapper.writeValueAsBytes(new InvalidRequestResponse());
+
         Page prevpage = mapper.readValue(prevpageStr, Page.class);
 
         InfoItemsPage<StreamInfoItem> info = ChannelInfo.getMoreItems(YOUTUBE_SERVICE,
@@ -388,6 +391,9 @@ public class ResponseHelper {
     public static byte[] playlistPageResponse(String playlistId, String prevpageStr)
             throws IOException, ExtractionException {
 
+        if (StringUtils.isEmpty(prevpageStr))
+            return mapper.writeValueAsBytes(new InvalidRequestResponse());
+
         Page prevpage = mapper.readValue(prevpageStr, Page.class);
 
         InfoItemsPage<StreamInfoItem> info = PlaylistInfo.getMoreItems(YOUTUBE_SERVICE,
@@ -552,6 +558,9 @@ public class ResponseHelper {
     public static byte[] searchPageResponse(String q, String filter, String prevpageStr)
             throws IOException, ExtractionException {
 
+        if (StringUtils.isEmpty(prevpageStr))
+            return mapper.writeValueAsBytes(new InvalidRequestResponse());
+
         Page prevpage = mapper.readValue(prevpageStr, Page.class);
 
         InfoItemsPage<InfoItem> pages = SearchInfo.getMoreItems(YOUTUBE_SERVICE,
@@ -622,6 +631,9 @@ public class ResponseHelper {
 
     public static byte[] commentsPageResponse(String videoId, String prevpageStr) throws Exception {
 
+        if (StringUtils.isEmpty(prevpageStr))
+            return mapper.writeValueAsBytes(new InvalidRequestResponse());
+
         Page prevpage = mapper.readValue(prevpageStr, Page.class);
 
         InfoItemsPage<CommentsInfoItem> info = CommentsInfo.getMoreItems(YOUTUBE_SERVICE, "https://www.youtube.com/watch?v=" + videoId, prevpage);