diff --git a/calibre-plugin/config.py b/calibre-plugin/config.py
index 5531cb9..0f3fa31 100644
--- a/calibre-plugin/config.py
+++ b/calibre-plugin/config.py
@@ -498,7 +498,10 @@ class ConfigWidget(QWidget):
         except:
             pass
         if ade_mail is None: 
-            self.button_convert_anon_to_account.setEnabled(False)
+            try: 
+                self.button_convert_anon_to_account.setEnabled(False)
+            except:
+                pass
         self.button_export_activation.setEnabled(False)
         self.button_export_key.setEnabled(False)
         self.lblAccInfo.setText("Authorization deleted.\nClose and re-open this window to add a new authorization.")
diff --git a/calibre-plugin/libadobe.py b/calibre-plugin/libadobe.py
index ade078d..7ae29e5 100644
--- a/calibre-plugin/libadobe.py
+++ b/calibre-plugin/libadobe.py
@@ -51,6 +51,7 @@ VAR_VER_OS_IDENTIFIERS = [ "Windows Vista", "Windows Vista", "Windows 8", "Windo
 
 # "Missing" versions:
 # 1.7.1, 2.0, 3.0, 4.0, 4.0.1, 4.0.2, 4.5 to 4.5.9
+# 4.5.7.179634
 
 # This is a list of ALL versions we know (and can potentially use if present in a config file).
 # Must have the same length / size as the four lists above.
@@ -67,6 +68,11 @@ VAR_VER_ALLOWED_BUILD_IDS_SWITCH_TO = [ 1131, 78765, 91394, 123281, 187303 ]
 # According to changelogs, this is implemented as of ADE 4.0.1 - no idea what build ID that is.
 VAR_VER_NEED_HTTPS_BUILD_ID_LIMIT = 123281
 
+# Versions >= this are using a different order for the XML elements in a FulfillmentNotification.
+# This doesn't matter for fulfillment at all, but I want to emulate ADE as accurately as possible.
+# Implemented as of ADE 4.0.0, no idea what exact build number that is.
+VAR_VER_USE_DIFFERENT_NOTIFICATION_XML_ORDER = 123281
+
 # Default build ID to use - ADE 2.0.1
 VAR_VER_DEFAULT_BUILD_ID = 78765
 
diff --git a/calibre-plugin/libadobeAccount.py b/calibre-plugin/libadobeAccount.py
index ae201b4..81dd6c6 100644
--- a/calibre-plugin/libadobeAccount.py
+++ b/calibre-plugin/libadobeAccount.py
@@ -711,6 +711,10 @@ def buildActivateReq(useVersionIndex: int = 0):
 
     ret += "<adept:fingerprint>%s</adept:fingerprint>" % (devicexml.find("./%s" % (adNS("fingerprint"))).text)
 
+    # TODO: Here's where multiple <adept:activationToken>s, each with a user and a device,
+    # TODO: would show up if the client was already activated and just adds an additional activation.
+    # TODO: Not sure if I want to replicate this, or if I'd rather replicate independant installations ...
+
     ret += "</adept:targetDevice>"
 
     ret += addNonce()
diff --git a/calibre-plugin/libadobeFulfill.py b/calibre-plugin/libadobeFulfill.py
index a1fbd7c..893e736 100644
--- a/calibre-plugin/libadobeFulfill.py
+++ b/calibre-plugin/libadobeFulfill.py
@@ -5,10 +5,12 @@ try:
     from libadobe import addNonce, sign_node, get_cert_from_pkcs12, sendRequestDocu, sendRequestDocuRC, sendHTTPRequest
     from libadobe import get_devkey_path, get_device_path, get_activation_xml_path
     from libadobe import VAR_VER_SUPP_VERSIONS, VAR_VER_SUPP_CONFIG_NAMES, VAR_VER_HOBBES_VERSIONS
+    from libadobe import VAR_VER_BUILD_IDS, VAR_VER_USE_DIFFERENT_NOTIFICATION_XML_ORDER
 except: 
     from calibre_plugins.deacsm.libadobe import addNonce, sign_node, get_cert_from_pkcs12, sendRequestDocu, sendRequestDocuRC, sendHTTPRequest
     from calibre_plugins.deacsm.libadobe import get_devkey_path, get_device_path, get_activation_xml_path
     from calibre_plugins.deacsm.libadobe import VAR_VER_SUPP_VERSIONS, VAR_VER_SUPP_CONFIG_NAMES, VAR_VER_HOBBES_VERSIONS
+    from calibre_plugins.deacsm.libadobe import VAR_VER_BUILD_IDS, VAR_VER_USE_DIFFERENT_NOTIFICATION_XML_ORDER
 
  
 def buildFulfillRequest(acsm):
@@ -658,8 +660,32 @@ def performFulfillmentNotification(fulfillmentResultToken, forceOptional = False
         full_text = "<adept:notification xmlns:adept=\"http://ns.adobe.com/adept\">"
         full_text += "<adept:user>%s</adept:user>" % user
         full_text += "<adept:device>%s</adept:device>" % device
-        full_text += etree.tostring(body, encoding="utf-8", pretty_print=True, xml_declaration=False).decode("utf-8")
-        full_text += addNonce()
+
+
+        # ADE 4.0 apparently changed the order of these two elements. 
+        # I still don't know exactly how this order is determined, but in most cases
+        # ADE 4+ has the body first, then the nonce, while ADE 3 and lower usually has nonce first, then body.
+        # It probably doesn't matter, but still, we want to behave exactly like ADE, so check the version number: 
+
+        devicexml = etree.parse(get_device_path())
+        for f in devicexml.findall("./%s" % (adNS("version"))):
+            if f.get("name") == "hobbes":
+                version = f.get("value")
+
+        try: 
+            v_idx = VAR_VER_HOBBES_VERSIONS.index(version)
+            clientVersion = VAR_VER_BUILD_IDS[v_idx]
+        except:
+            clientVersion = 0
+        
+        if (clientVersion >= VAR_VER_USE_DIFFERENT_NOTIFICATION_XML_ORDER):
+            full_text += etree.tostring(body, encoding="utf-8", pretty_print=True, xml_declaration=False).decode("utf-8")
+            full_text += addNonce()
+        else:
+            full_text += addNonce()
+            full_text += etree.tostring(body, encoding="utf-8", pretty_print=True, xml_declaration=False).decode("utf-8")
+            
+
         full_text += "</adept:notification>"