diff --git a/gui/wxpython/iscatt/core_c.py b/gui/wxpython/iscatt/core_c.py
index 93f90e6a2ee..1af6fe11186 100644
--- a/gui/wxpython/iscatt/core_c.py
+++ b/gui/wxpython/iscatt/core_c.py
@@ -82,7 +82,8 @@ def ApplyColormap(vals, vals_mask, colmap, out_vals):
 
 def MergeArrays(merged_arr, overlay_arr, alpha):
     if merged_arr.shape != overlay_arr.shape:
-        GException("MergeArrays: merged_arr.shape != overlay_arr.shape")
+        msg = "MergeArrays: merged_arr.shape != overlay_arr.shape"
+        raise GException(msg)
 
     c_uint8_p = POINTER(c_uint8)
     merged_p = merged_arr.ctypes.data_as(c_uint8_p)
diff --git a/gui/wxpython/iscatt/iscatt_core.py b/gui/wxpython/iscatt/iscatt_core.py
index 8ad40df672a..063e2cca08b 100644
--- a/gui/wxpython/iscatt/iscatt_core.py
+++ b/gui/wxpython/iscatt/iscatt_core.py
@@ -139,7 +139,7 @@ def ComputeCatsScatts(self, cats_ids):
         )
 
         if returncode < 0:
-            GException(_("Computing of scatter plots failed."))
+            raise GException(_("Computing of scatter plots failed."))
 
     def CatRastUpdater(self):
         return self.cat_rast_updater
@@ -274,7 +274,7 @@ def _updateCatRast(self, bbox, areas_cats, updated_cats):
             region = self.an_data.GetRegion()
             ret = UpdateCatRast(patch_rast, region, self.scatts_dt.GetCatRastCond(cat))
             if ret < 0:
-                GException(_("Patching category raster conditions file failed."))
+                raise GException(_("Patching category raster conditions file failed."))
             RunCommand("g.remove", flags="f", type="raster", name=patch_rast)
 
     def _rasterize(self, grass_region, layer, cat, out_rast):
@@ -296,7 +296,7 @@ def _rasterize(self, grass_region, layer, cat, out_rast):
         )
 
         if ret != 0:
-            GException(_("v.build failed:\n%s") % msg)
+            raise GException(_("v.build failed:\n%s") % msg)
 
         environs = os.environ.copy()
         environs["GRASS_REGION"] = grass_region["GRASS_REGION"]
@@ -316,7 +316,7 @@ def _rasterize(self, grass_region, layer, cat, out_rast):
         )
 
         if ret != 0:
-            GException(_("v.to.rast failed:\n{messages}").format(messages=msg))
+            raise GException(_("v.to.rast failed:\n{messages}").format(messages=msg))
 
     def _create_grass_region_env(self, bbox):
         r = self.an_data.GetRegion()
@@ -383,7 +383,8 @@ def Create(self, bands):
 
         self.region = GetRegion()
         if self.region["rows"] * self.region["cols"] > MAX_NCELLS:
-            GException("too big region")
+            msg = "too big region"
+            raise GException(msg)
 
         self.bands_info = {}
 
@@ -391,7 +392,7 @@ def Create(self, bands):
             i = GetRasterInfo(b)
 
             if i is None:
-                GException("raster %s is not CELL type" % (b))
+                raise GException("raster %s is not CELL type" % (b))
 
             self.bands_info[b] = i
             # TODO check size of raster