diff --git a/TODO.md b/TODO.md
index 5b3e4775..c52bfeff 100644
--- a/TODO.md
+++ b/TODO.md
@@ -4,8 +4,6 @@
   - Handle upload errors: non existent path, path is a dir, file too big, etc
   - Show real progression for mxc thumbnail loadings, uploads and downloads
 
-  - Login & upload: use new exception python/qml mechanism
-
   - Support m.file thumbnails
   - Generate video thumbnails
   - GIFs can use the video player
@@ -201,6 +199,12 @@
   - Support "Empty room (was ...)" after peer left
   - Previewing room without joining
 
+  - thumbnail API shouldn't require auth
+  - get content repo config API
+  - add the `resume()` method
+
+  - See if we can turn all the Error classes into actual exceptions
+
 - Distribution
   - Include python dependencies in binary with rcc?
   - README.md
diff --git a/src/python/backend.py b/src/python/backend.py
index 284db60a..2dd007b7 100644
--- a/src/python/backend.py
+++ b/src/python/backend.py
@@ -8,7 +8,7 @@ import hsluv
 import nio
 
 from .app import App
-from .matrix_client import MatrixClient
+from .matrix_client import MatrixClient, MatrixError
 from .models.items import Account, Device, Event, Member, Room, Upload
 from .models.model_store import ModelStore
 
@@ -51,7 +51,7 @@ class Backend:
         password:   str,
         device_id:  Optional[str] = None,
         homeserver: str           = "https://matrix.org",
-    ) -> Tuple[bool, str]:
+   ) -> str:
 
         client = MatrixClient(
             self, user=user, homeserver=homeserver, device_id=device_id,
@@ -59,13 +59,13 @@ class Backend:
 
         try:
             await client.login(password)
-        except RuntimeError as err:  # XXX raise
+        except MatrixError:
             await client.close()
-            return (False, err.args[0].message)
+            raise
 
         self.clients[client.user_id]         = client
         self.models[Account][client.user_id] = Account(client.user_id)
-        return (True, client.user_id)
+        return client.user_id
 
 
     async def resume_client(self,
diff --git a/src/python/matrix_client.py b/src/python/matrix_client.py
index 2a45e6d3..639ddcd4 100644
--- a/src/python/matrix_client.py
+++ b/src/python/matrix_client.py
@@ -41,6 +41,8 @@ class MatrixError(Exception):
 
     @classmethod
     def from_nio(cls, response: nio.ErrorResponse) -> "MatrixError":
+        # Check for the M_CODE first: some errors for an API share the same
+        # http code, but have different M_CODEs (e.g. POST /login 403).
         for subcls in cls.__subclasses__():
             if subcls.m_code == response.status_code:
                 return subcls()
@@ -58,6 +60,12 @@ class MatrixForbidden(MatrixError):
     m_code:    str = "M_FORBIDDEN"
 
 
+@dataclass
+class MatrixUserDeactivated(MatrixError):
+    http_code: int = 403
+    m_code:    str = "M_USER_DEACTIVATED"
+
+
 @dataclass
 class MatrixNotFound(MatrixError):
     http_code: int = 404
@@ -159,7 +167,7 @@ class MatrixClient(nio.AsyncClient):
         )
 
         if isinstance(response, nio.LoginError):
-            raise RuntimeError(response)
+            raise MatrixError.from_nio(response)
 
         asyncio.ensure_future(self.start())
 
diff --git a/src/qml/Pages/SignIn.qml b/src/qml/Pages/SignIn.qml
index c09c0ff3..22044225 100644
--- a/src/qml/Pages/SignIn.qml
+++ b/src/qml/Pages/SignIn.qml
@@ -34,23 +34,33 @@ HPage {
                     undefined, serverField.text,
                 ]
 
-                py.callCoro("login_client", args, ([success, data]) => {
-                    if (! success) {
-                        errorMessage.text = qsTr(data)
-                        button.loading    = false
-                        return
-                    }
+                loginTimeout.restart()
+
+                py.callCoro("login_client", args, userId => {
+                    loginTimeout.stop()
+                    errorMessage.text = ""
+                    button.loading    = false
 
                     py.callCoro(
                         "saved_accounts." +
                         (rememberAccount.checked ? "add": "delete"),
                         [data]
                     )
+
                     pageLoader.showPage(
                         "AccountSettings/AccountSettings", {userId: data}
                     )
+                }, type => {
+                    loginTimeout.stop()
+                    let txt = qsTr("Invalid request or login type")
 
-                    errorMessage.text = ""
+                    if (type === "MatrixForbidden")
+                        txt = qsTr("Invalid username or password")
+
+                    if (type === "MatrixUserDeactivated")
+                        txt = qsTr("This account was deactivated")
+
+                    errorMessage.text = txt
                     button.loading    = false
                 })
             },
@@ -58,6 +68,17 @@ HPage {
             forgot: button => {}
         })
 
+        Timer {
+            id: loginTimeout
+            interval: 30 * 1000
+            onTriggered: {
+                errorMessage.text = qsTr(
+                    "This server seems unavailable. Verify your internet " +
+                    "connection or try again in a few minutes."
+                )
+            }
+        }
+
         HRowLayout {
             spacing: signInBox.horizontalSpacing * 1.25
             Layout.alignment: Qt.AlignHCenter