diff --git a/library/src/main/java/com/github/javiersantos/appupdater/AppUpdater.java b/library/src/main/java/com/github/javiersantos/appupdater/AppUpdater.java
index a893aa1f..8badb338 100644
--- a/library/src/main/java/com/github/javiersantos/appupdater/AppUpdater.java
+++ b/library/src/main/java/com/github/javiersantos/appupdater/AppUpdater.java
@@ -255,6 +255,10 @@ public void onSuccess(Update update) {
             public void onFailed(AppUpdaterError error) {
                 if (error == AppUpdaterError.UPDATE_VARIES_BY_DEVICE) {
                     Log.e("AppUpdater", "UpdateFrom.GOOGLE_PLAY isn't valid: update varies by device.");
+                } else if (error == AppUpdaterError.GITHUB_USER_REPO_INVALID) {
+                    throw new IllegalArgumentException("GitHub user or repo is empty!");
+                } else if (error == AppUpdaterError.XML_URL_INVALID) {
+                    throw new IllegalArgumentException("XML file is not valid!");
                 }
             }
         });
diff --git a/library/src/main/java/com/github/javiersantos/appupdater/UtilsAsync.java b/library/src/main/java/com/github/javiersantos/appupdater/UtilsAsync.java
index 33320d31..fa6aba92 100644
--- a/library/src/main/java/com/github/javiersantos/appupdater/UtilsAsync.java
+++ b/library/src/main/java/com/github/javiersantos/appupdater/UtilsAsync.java
@@ -37,13 +37,16 @@ protected void onPreExecute() {
                 if (!fromUtils && !libraryPreferences.getAppUpdaterShow()) {
                     cancel(true);
                 } else {
-                    if (updateFrom == UpdateFrom.GITHUB) {
-                        if (!GitHub.isGitHubValid(gitHub)) {
-                            cancel(true);
-                        }
+                    if (updateFrom == UpdateFrom.GITHUB && !GitHub.isGitHubValid(gitHub)) {
+                        listener.onFailed(AppUpdaterError.GITHUB_USER_REPO_INVALID);
+                        cancel(true);
+                    } else if (updateFrom == UpdateFrom.XML && (xmlUrl == null || !UtilsLibrary.isStringAnUrl(xmlUrl))) {
+                        listener.onFailed(AppUpdaterError.XML_URL_INVALID);
+                        cancel(true);
                     }
                 }
             } else {
+                listener.onFailed(AppUpdaterError.NETWORK_NOT_AVAILABLE);
                 cancel(true);
             }
         }
diff --git a/library/src/main/java/com/github/javiersantos/appupdater/UtilsLibrary.java b/library/src/main/java/com/github/javiersantos/appupdater/UtilsLibrary.java
index 603c0300..87d7f40c 100644
--- a/library/src/main/java/com/github/javiersantos/appupdater/UtilsLibrary.java
+++ b/library/src/main/java/com/github/javiersantos/appupdater/UtilsLibrary.java
@@ -62,6 +62,16 @@ static Boolean isStringAVersion(String version) {
         return version.matches(".*\\d+.*");
     }
 
+    static Boolean isStringAnUrl(String s) {
+        Boolean res = false;
+        try {
+            new URL(s);
+            res = true;
+        } catch (MalformedURLException ignored) {}
+
+        return res;
+    }
+
     static Boolean getDurationEnumToBoolean(Duration duration) {
         Boolean res = false;
 
@@ -152,8 +162,7 @@ static Update getLatestAppVersionHttp(Context context, UpdateFrom updateFrom, Gi
             source = str.toString();
         } catch (FileNotFoundException e) {
             Log.e("AppUpdater", "App wasn't found in the provided source. Is it published?");
-        } catch (IOException ignore) {
-        }
+        } catch (IOException ignore) {}
 
         if (isAvailable) {
             switch (updateFrom) {
diff --git a/library/src/main/java/com/github/javiersantos/appupdater/enums/AppUpdaterError.java b/library/src/main/java/com/github/javiersantos/appupdater/enums/AppUpdaterError.java
index e3a8e7fb..cb52ce18 100644
--- a/library/src/main/java/com/github/javiersantos/appupdater/enums/AppUpdaterError.java
+++ b/library/src/main/java/com/github/javiersantos/appupdater/enums/AppUpdaterError.java
@@ -1,5 +1,23 @@
 package com.github.javiersantos.appupdater.enums;
 
 public enum AppUpdaterError {
-    UPDATE_VARIES_BY_DEVICE
+    /**
+     * Google Play returned "Varies by device"
+     */
+    UPDATE_VARIES_BY_DEVICE,
+
+    /**
+     * GitHub user or repo is empty
+     */
+    GITHUB_USER_REPO_INVALID,
+
+    /**
+     * No Internet connection available
+     */
+    NETWORK_NOT_AVAILABLE,
+
+    /**
+     * URL for the XML file is not valid
+     */
+    XML_URL_INVALID
 }
diff --git a/library/src/main/java/com/github/javiersantos/appupdater/objects/GitHub.java b/library/src/main/java/com/github/javiersantos/appupdater/objects/GitHub.java
index c4559c8a..e13e937d 100644
--- a/library/src/main/java/com/github/javiersantos/appupdater/objects/GitHub.java
+++ b/library/src/main/java/com/github/javiersantos/appupdater/objects/GitHub.java
@@ -1,7 +1,5 @@
 package com.github.javiersantos.appupdater.objects;
 
-import android.util.Log;
-
 public class GitHub {
     private String gitHubUser;
     private String gitHubRepo;
@@ -29,7 +27,6 @@ public void setGitHubRepo(String repo) {
 
     public static Boolean isGitHubValid(GitHub gitHub) {
         if (gitHub == null || gitHub.getGitHubUser().length() == 0 || gitHub.getGitHubRepo().length() == 0) {
-            Log.e("AppUpdater", "GitHub user or repo is empty!!");
             return false;
         } else {
             return true;