diff --git a/applications/luci-app-attendedsysupgrade/root/www/luci-static/resources/attendedsysupgrade.js b/applications/luci-app-attendedsysupgrade/root/www/luci-static/resources/attendedsysupgrade.js
index 2cf5cc6e1b..9cfd1bc7a6 100644
--- a/applications/luci-app-attendedsysupgrade/root/www/luci-static/resources/attendedsysupgrade.js
+++ b/applications/luci-app-attendedsysupgrade/root/www/luci-static/resources/attendedsysupgrade.js
@@ -58,21 +58,6 @@ function edit_packages() {
     show("#edit_packages");
 }
 
-// requests to the upgrade server
-function server_request(path, callback) {
-    var request = new XMLHttpRequest();
-    request.open("POST", data.url + "/" + path, true);
-    request.setRequestHeader("Content-type", "application/json");
-    request.send(JSON.stringify(request_dict));
-    request.onerror = function(e) {
-        set_status("danger", "upgrade server down")
-        show("#server_div");
-    }
-    request.addEventListener('load', function(event) {
-        callback(request)
-    });
-}
-
 // initial setup, get system information
 function setup() {
     ubus_call("rpc-sys", "packagelist", {}, "packages");
@@ -163,57 +148,74 @@ function set_status(type, message, loading, show_log) {
     if (loading) {
         loading_image = '<img src="/luci-static/resources/icons/loading.gif" alt="Loading" style="vertical-align:middle"> ';
     }
-    if (show_log && data.log) {
-        message += ' <p><a target="_blank" href="' + data.url + data.log + '">Build log</a></p>'
+    if (data.buildlog_url && show_log) {
+        message += ' <p><a target="_blank" href="' + data.buildlog_url + '">Build log</a></p>'
     }
     $("#status_box").innerHTML = loading_image + message;
     show("#status_box")
 }
 
 function upgrade_check() {
-    // Asks server for new firmware
-    // If data.upgrade_packages is set to true search for new package versions as well
+    var current_version = data.release.version.toLowerCase();
+    var current_branch = current_version.split('.').slice(0, 2).join('.')
+    var candidates = []
     hide("#status_box");
     hide("#server_div");
     set_status("info", "Searching for upgrades", true);
-    request_dict.distro = data.release.distribution;
-    request_dict.version = data.release.version;
-    request_dict.target = data.release.target;
-    request_dict.revision = data.release.revision;
-    request_dict.installed = data.packages;
-    request_dict.upgrade_packages = data.upgrade_packages
-    server_request("api/upgrade-check", upgrade_check_callback)
-}
+    fetch(data.url + "/api/versions")
+        .then(response => response.json())
+        .then(response => {
+            var branches = response["branches"]
+            for (i in branches) {
+                // handle snapshots in a special way - as always
+                if (current_version == "snapshot" && branches[i]["latest"] == "snapshot") {
+                    candidates.unshift(branches[i])
+                    break
+                }
 
-function upgrade_check_callback(request_text) {
-    var request_json = JSON.parse(request_text)
-
-    // create simple output to tell user what's going to be upgrade (release/packages)
-    var info_output = ""
-    if (request_json.version) {
-        info_output += "<h3>New release <b>" + request_json.version + "</b> available</h3>"
-        info_output += "Installed version: " + data.release.version
-        request_dict.version = request_json.version;
-    }
-    if (request_json.upgrades) {
-        if (request_json.upgrades != {}) {
-            info_output += "<h3>Package upgrades available</h3>"
-            for (var upgrade in request_json.upgrades) {
-                info_output += "<b>" + upgrade + "</b>: " + request_json.upgrades[upgrade][1] + " to " + request_json.upgrades[upgrade][0] + "<br />"
+                if (current_version == branches[i]["latest"]) {
+                    break
+                }
+                if (current_branch != branches[i]["name"]) {
+                    branches[i]["warn_branch_jump"] = true
+                }
+                candidates.unshift(branches[i])
+                if (current_branch == branches[i]["name"]) {
+                    // don't offer branches older than the current
+                    break
+                }
             }
-        }
-    }
-    data.packages = request_json.packages
-    set_status("success", info_output)
 
-    if (data.advanced_mode == 1) {
-        show("#edit_button");
-    }
-    var upgrade_button = $("#upgrade_button")
-    upgrade_button.value = "Request firmware";
-    upgrade_button.style.display = "block";
-    upgrade_button.disabled = false;
-    upgrade_button.onclick = upgrade_request;
+            if (candidates.length > 0) {
+                var info_output = "<h3>New release <b>" + candidates[0].latest + "</b> available</h3>"
+                info_output += "Installed version: " + data.release.version
+
+                // tell server the currently installed version
+                request_dict.current_version = request_dict.version;
+                // tell server what version to install
+                request_dict.version = candidates[0].latest;
+                // tell server to diff the requested packages with the default packages
+                // this allows to not automatically re-install default packages which
+                // where dropped in later releases
+                request_dict.diff_packages = true;
+
+                set_status("success", info_output)
+
+                if (data.advanced_mode == 1) {
+                    show("#edit_button");
+                }
+                var upgrade_button = $("#upgrade_button")
+                upgrade_button.value = "Request firmware";
+                upgrade_button.style.display = "block";
+                upgrade_button.disabled = false;
+                upgrade_button.onclick = upgrade_request;
+
+            } else {
+                set_status("success", "No upgrades available")
+
+            }
+        });
+
 }
 
 function upgrade_request() {
@@ -224,37 +226,39 @@ function upgrade_request() {
     hide("#edit_button");
     hide("#keep_container");
 
-    // remove "installed" entry as unused by build requests
-    delete request_dict.installed
     // add board info to let server determine profile
-    request_dict.board_name = data.board_name
-    request_dict.board = data.board_name
-    request_dict.model = data.model
+    request_dict.profile = data.board_name
 
     if (data.edit_packages == true) {
         request_dict.packages = $("#edit_packages").value.split("\n")
     } else {
-        request_dict.packages = data.packages;
+        request_dict.packages = Object.keys(data.packages);
     }
-    server_request("api/upgrade-request", upgrade_request_callback)
+    server_request()
 }
 
-function upgrade_request_callback(request) {
-    // ready to download
-    var request_json = JSON.parse(request)
-    data.files = request_json.files
-    data.sysupgrade = request_json.sysupgrade
-    data.log = request_json.log
+function upgrade_request_callback(response) {
+    var sysupgrade_file = "";
+    console.log(response)
+    for (i in response.images) {
+        if (response.images[i].type == "sysupgrade") {
+            sysupgrade_file = response.images[i].name;
+        }
+    }
+    if (sysupgrade_file != "") {
+        data.sysupgrade_url = data.url + '/store/' + response.bin_dir + '/' + sysupgrade_file
+        var info_output = '<h3>Firmware created</h3><p>Created file: <a href="' + data.sysupgrade_url + '">' + sysupgrade_file + '</p></a>'
+        set_status("success", info_output, false, true);
 
-    var info_output = '<h3>Firmware created</h3><p>Created file: <a href="' + data.url + data.files + data.sysupgrade + '">' + data.sysupgrade + '</p></a>'
-    set_status("success", info_output, false, true);
-
-    show("#keep_container");
-    var upgrade_button = $("#upgrade_button")
-    upgrade_button.disabled = false;
-    upgrade_button.style.display = "block";
-    upgrade_button.value = "Flash firmware";
-    upgrade_button.onclick = download_image;
+        show("#keep_container");
+        var upgrade_button = $("#upgrade_button")
+        upgrade_button.disabled = false;
+        upgrade_button.style.display = "block";
+        upgrade_button.value = "Flash firmware";
+        upgrade_button.onclick = download_image;
+    } else {
+        set_status("danger", "Firmware build successfull but device not sysupgrade compatible!")
+    }
 }
 
 function flash_image() {
@@ -323,7 +327,7 @@ function download_image() {
     hide("#keep_container");
     hide("#upgrade_button");
     var download_request = new XMLHttpRequest();
-    download_request.open("GET", data.url + data.files + data.sysupgrade);
+    download_request.open("GET", data.sysupgrade_url);
     download_request.responseType = "arraybuffer";
 
     download_request.onload = function() {
@@ -338,90 +342,43 @@ function download_image() {
     download_request.send();
 }
 
-function server_request(path, callback) {
-    var request_json;
-    var request = new XMLHttpRequest();
-    request.open("POST", data.url + "/" + path, true);
-    request.setRequestHeader("Content-type", "application/json");
-    request.send(JSON.stringify(request_dict));
-    request.onerror = function(e) {
-        set_status("danger", "Upgrade server down or could not connect")
-        show("#server_div");
-    }
-    request.addEventListener('load', function(event) {
-        var request_text = request.responseText;
-        if (request.status === 200) {
-            callback(request_text)
-
-        } else if (request.status === 202) {
-            var imagebuilder = request.getResponseHeader("X-Imagebuilder-Status");
-            if (imagebuilder === "queue") {
-                // in queue
-                var queue = request.getResponseHeader("X-Build-Queue-Position");
-                set_status("info", "In build queue position " + queue, true)
-                console.log("queued");
-            } else if (imagebuilder === "building") {
-                set_status("info", "Building image", true);
-                console.log("building");
-            } else {
-                // fallback if for some reasons the headers are missing e.g. browser blocks access
-                set_status("info", "Processing request", true);
-                console.log(imagebuilder)
+function server_request() {
+    fetch(data.url + "/api/build", {
+            method: 'POST',
+            headers: {
+                'Content-Type': 'application/json'
+            },
+            body: JSON.stringify(request_dict)
+        })
+        .then(response => {
+            switch (response.status) {
+                case 200:
+                    response.json()
+                        .then(response => {
+                            upgrade_request_callback(response)
+                        });
+                    break;
+                case 202:
+                    set_status("info", "Processing request", true);
+                    setTimeout(function() {
+                        server_request()
+                    }, 5000)
+                    break;
+                case 400: // bad request
+                case 422: // bad package
+                case 500: // build failed
+                    console.log('error (' + response.status + ')');
+                    response.json()
+                        .then(response => {
+                            if (response.buildlog) {
+                                data.buildlog_url = data.url + '/' + response.bin_dir + '/buildlog.txt';
+                            }
+                            set_status("danger", response.message);
+                        });
+                    break;
             }
-            setTimeout(function() {
-                server_request(path, callback)
-            }, 5000)
-
-        } else if (request.status === 204) {
-            // no upgrades available
-            set_status("success", "No upgrades available")
-
-        } else if (request.status === 400) {
-            // bad request
-            request_json = JSON.parse(request_text)
-            set_status("danger", request_json.error)
-
-        } else if (request.status === 409) {
-            // bad request
-            request_json = JSON.parse(request_text)
-            data.log = request_json.log
-            set_status("danger", "Incompatible package selection. See build log for details", false, true)
-
-        } else if (request.status === 412) {
-            // this is a bit generic
-            set_status("danger", "Unsupported device, release, target, subtraget or board")
-
-        } else if (request.status === 413) {
-            set_status("danger", "No firmware created due to image size. Try again with less packages selected.")
-
-        } else if (request.status === 422) {
-            var package_missing = request.getResponseHeader("X-Unknown-Package");
-            set_status("danger", "Unknown package in request: <b>" + package_missing + "</b>")
-        } else if (request.status === 500) {
-            request_json = JSON.parse(request_text)
-
-            var error_box_content = "<b>Internal server error</b><br />"
-            error_box_content += request_json.error
-            if (request_json.log != undefined) {
-                data.log = request_json.log
-            }
-            set_status("danger", error_box_content, false, true)
-
-        } else if (request.status === 501) {
-            set_status("danger", "No sysupgrade file produced, may not supported by model.")
-        } else if (request.status === 502) {
-            // python part offline
-            set_status("danger", "Server down for maintenance")
-            setTimeout(function() {
-                server_request(path, callback)
-            }, 30000)
-        } else if (request.status === 503) {
-            set_status("danger", "Server overloaded")
-            setTimeout(function() {
-                server_request(path, callback)
-            }, 30000)
-        }
-    });
+        });
 }
+
 request_dict = {}
 document.onload = setup()