diff --git a/yt/visualization/base_plot_types.py b/yt/visualization/base_plot_types.py
index 716ee7c9bd5..263a563f695 100644
--- a/yt/visualization/base_plot_types.py
+++ b/yt/visualization/base_plot_types.py
@@ -49,8 +49,8 @@ class FormatKwargs(TypedDict):
     "GTKAgg": ["backend_gtkagg", "FigureCanvasGTKAgg", None],
     "GTKCairo": ["backend_gtkcairo", "FigureCanvasGTKCairo", None],
     "MacOSX": ["backend_macosx", "FigureCanvasMac", "FigureManagerMac"],
-    "Qt4Agg": ["backend_qt4agg", "FigureCanvasQTAgg", None],
     "Qt5Agg": ["backend_qt5agg", "FigureCanvasQTAgg", None],
+    "QtAgg": ["backend_qtagg", "FigureCanvasQTAgg", None],
     "TkAgg": ["backend_tkagg", "FigureCanvasTkAgg", None],
     "WX": ["backend_wx", "FigureCanvasWx", None],
     "WXAgg": ["backend_wxagg", "FigureCanvasWxAgg", None],
@@ -155,10 +155,7 @@ def _get_canvas_classes(self):
         else:
             key = "agg"
 
-        try:
-            module, fig_canvas, fig_manager = BACKEND_SPECS[key]
-        except KeyError:
-            return
+        module, fig_canvas, fig_manager = BACKEND_SPECS[key]
 
         mod = __import__(
             "matplotlib.backends",