diff --git a/WebAPI_Changelog.md b/WebAPI_Changelog.md
index 7be0c987a..19dafdedc 100644
--- a/WebAPI_Changelog.md
+++ b/WebAPI_Changelog.md
@@ -1,5 +1,13 @@
 # WebAPI Changelog
 
+## 2.14.0
+* [#23202](https://github.com/qbittorrent/qBittorrent/pull/23202)
+  * WebAPI responds with the error message "Endpoint does not exist" when the endpoint does not exist, to better differentiate from unrelated Not Found (i.e. 404) responses
+  * `auth/login` endpoint responds to invalid credentials with a 401
+  * `torrents/add` endpoint responds with `success_count`, `pending_count`, `failure_count`, and `added_torrent_ids`
+    * When `pending_count` is non-zero, response code 202 is used
+    * When all torrents fail to be added, response code 409 is used
+
 ## 2.13.1
 * [#23163](https://github.com/qbittorrent/qBittorrent/pull/23163)
   * `torrents/add` endpoint now supports downloading from a search plugin via the `downloader` parameter
diff --git a/src/webui/api/apicontroller.cpp b/src/webui/api/apicontroller.cpp
index 494bff280..e1b9d52b5 100644
--- a/src/webui/api/apicontroller.cpp
+++ b/src/webui/api/apicontroller.cpp
@@ -59,7 +59,7 @@ APIResult APIController::run(const QString &action, const StringMap &params, con
 
     const QByteArray methodName = action.toLatin1() + "Action";
     if (!QMetaObject::invokeMethod(this, methodName.constData()))
-        throw APIError(APIErrorType::NotFound);
+        throw APIError(APIErrorType::NotFound, tr("Endpoint does not exist"));
 
     return m_result;
 }
diff --git a/src/webui/api/apierror.h b/src/webui/api/apierror.h
index 3879bd3af..b0a87828f 100644
--- a/src/webui/api/apierror.h
+++ b/src/webui/api/apierror.h
@@ -32,11 +32,12 @@
 
 enum class APIErrorType
 {
+    AccessDenied,
     BadParams,
     BadData,
+    Conflict,
     NotFound,
-    AccessDenied,
-    Conflict
+    Unauthorized
 };
 
 class APIError : public RuntimeError
diff --git a/src/webui/api/authcontroller.cpp b/src/webui/api/authcontroller.cpp
index ee52c1df6..c2db0d596 100644
--- a/src/webui/api/authcontroller.cpp
+++ b/src/webui/api/authcontroller.cpp
@@ -59,7 +59,7 @@ void AuthController::loginAction()
 {
     if (m_sessionManager->session())
     {
-        setResult(u"Ok."_s);
+        setStatus(APIStatus::Ok);
         return;
     }
 
@@ -84,17 +84,17 @@ void AuthController::loginAction()
         m_clientFailedLogins.remove(clientAddr);
 
         m_sessionManager->sessionStart();
-        setResult(u"Ok."_s);
+        setStatus(APIStatus::Ok);
         LogMsg(tr("WebAPI login success. IP: %1").arg(clientAddr));
     }
     else
     {
         if (Preferences::instance()->getWebUIMaxAuthFailCount() > 0)
             increaseFailedAttempts();
-        setResult(u"Fails."_s);
         LogMsg(tr("WebAPI login failure. Reason: invalid credentials, attempt count: %1, IP: %2, username: %3")
                 .arg(QString::number(failedAttemptsCount()), clientAddr, usernameFromWeb)
             , Log::WARNING);
+        throw APIError(APIErrorType::Unauthorized);
     }
 }
 
diff --git a/src/webui/api/torrentscontroller.cpp b/src/webui/api/torrentscontroller.cpp
index 76e1ca29b..9eeb183bc 100644
--- a/src/webui/api/torrentscontroller.cpp
+++ b/src/webui/api/torrentscontroller.cpp
@@ -1098,7 +1098,10 @@ void TorrentsController::addAction()
     };
 
 
-    bool partialSuccess = false;
+    int pending = 0;
+    int failure = 0;
+    QList<BitTorrent::TorrentID> addedTorrentIDs;
+    addedTorrentIDs.reserve(urls.size() + torrents.size());
     for (QString url : urls)
     {
         url = url.trimmed();
@@ -1123,7 +1126,14 @@ void TorrentsController::addAction()
                 addTorrentParams.filePriorities = filePriorities;
             }
 
-            partialSuccess |= BitTorrent::Session::instance()->addTorrent(torrentDescr, addTorrentParams);
+            if (BitTorrent::Session::instance()->addTorrent(torrentDescr, addTorrentParams))
+            {
+                addedTorrentIDs.append(torrentID);
+            }
+            else
+            {
+                ++failure;
+            }
         }
         else if (!downloaderParam.isEmpty())
         {
@@ -1137,14 +1147,29 @@ void TorrentsController::addAction()
                 app()->addTorrentManager()->addTorrent(torrentFilePath, addTorrentParams);
             });
             connect(downloadHandler, &SearchDownloadHandler::downloadFinished, downloadHandler, &SearchDownloadHandler::deleteLater);
-            partialSuccess = true;
+
+            ++pending;
         }
         else
         {
             if (!filePriorities.isEmpty())
                 throw APIError(APIErrorType::BadParams, tr("`filePriorities` may only be specified when metadata has already been fetched"));
 
-            partialSuccess |= app()->addTorrentManager()->addTorrent(url, addTorrentParams);
+            if (app()->addTorrentManager()->addTorrent(url, addTorrentParams))
+            {
+                if (infoHash.isValid())
+                {
+                    addedTorrentIDs.append(torrentID);
+                }
+                else
+                {
+                    ++pending;
+                }
+            }
+            else
+            {
+                ++failure;
+            }
         }
         m_torrentSourceCache.remove(url);
         m_torrentMetadataCache.remove(torrentID);
@@ -1155,7 +1180,15 @@ void TorrentsController::addAction()
     {
         if (const auto loadResult = BitTorrent::TorrentDescriptor::load(it.value()))
         {
-            partialSuccess |= BitTorrent::Session::instance()->addTorrent(loadResult.value(), addTorrentParams);
+            const BitTorrent::TorrentDescriptor &torrentDescr = loadResult.value();
+            if (BitTorrent::Session::instance()->addTorrent(torrentDescr, addTorrentParams))
+            {
+                addedTorrentIDs.append(torrentDescr.infoHash().toTorrentID());
+            }
+            else
+            {
+                ++failure;
+            }
         }
         else
         {
@@ -1163,10 +1196,25 @@ void TorrentsController::addAction()
         }
     }
 
-    if (partialSuccess)
-        setResult(u"Ok."_s);
+    if (!addedTorrentIDs.isEmpty() || (pending > 0))
+    {
+        QJsonArray ids;
+        for (const BitTorrent::TorrentID &torrentID : addedTorrentIDs)
+            ids.append(torrentID.toString());
+
+        setResult(QJsonObject {
+            {u"success_count"_s, addedTorrentIDs.size()},
+            {u"failure_count"_s, failure},
+            {u"pending_count"_s, pending},
+            {u"added_torrent_ids"_s, ids},
+        });
+        if (pending > 0)
+            setStatus(APIStatus::Async);
+    }
     else
-        setResult(u"Fails."_s);
+    {
+        throw APIError(APIErrorType::Conflict);
+    }
 }
 
 void TorrentsController::addTrackersAction()
diff --git a/src/webui/webapplication.cpp b/src/webui/webapplication.cpp
index b771a863c..d398f6559 100644
--- a/src/webui/webapplication.cpp
+++ b/src/webui/webapplication.cpp
@@ -418,6 +418,8 @@ void WebApplication::doProcessRequest()
             throw ConflictHTTPError(error.message());
         case APIErrorType::NotFound:
             throw NotFoundHTTPError(error.message());
+        case APIErrorType::Unauthorized:
+            throw UnauthorizedHTTPError(error.message());
         default:
             Q_UNREACHABLE();
             break;
diff --git a/src/webui/webapplication.h b/src/webui/webapplication.h
index 1e6a89076..41201caa9 100644
--- a/src/webui/webapplication.h
+++ b/src/webui/webapplication.h
@@ -53,7 +53,7 @@
 #include "base/utils/version.h"
 #include "api/isessionmanager.h"
 
-inline const Utils::Version<3, 2> API_VERSION {2, 13, 1};
+inline const Utils::Version<3, 2> API_VERSION {2, 14, 0};
 
 class APIController;
 class AuthController;
diff --git a/src/webui/www/public/scripts/login.js b/src/webui/www/public/scripts/login.js
index cbe45e606..149e405ae 100644
--- a/src/webui/www/public/scripts/login.js
+++ b/src/webui/www/public/scripts/login.js
@@ -45,12 +45,12 @@ const submitLoginForm = (event) => {
             })
         })
         .then(async (response) => {
-                const responseText = await response.text();
-                if (response.ok && (responseText === "Ok.")) {
+                if (response.ok) {
                     location.replace(location); // redirect
                     location.reload(true);
                 }
                 else {
+                    const responseText = await response.text();
                     errorMsgElement.textContent = `QBT_TR(Invalid Username or Password.)QBT_TR[CONTEXT=Login]\nQBT_TR(Server response:)QBT_TR[CONTEXT=Login] ${responseText}`;
                 }
             },