diff --git a/src/calibre/gui2/catalog/catalog_epub_mobi.ui b/src/calibre/gui2/catalog/catalog_epub_mobi.ui
index 4dff426ee6..8a180d7bfb 100644
--- a/src/calibre/gui2/catalog/catalog_epub_mobi.ui
+++ b/src/calibre/gui2/catalog/catalog_epub_mobi.ui
@@ -726,7 +726,7 @@ The default pattern \[.+\]|\+ excludes tags of the form [tag], e.g., [Test book]
                   <double>1.000000000000000</double>
                  </property>
                  <property name="maximum">
-                  <double>5.000000000000000</double>
+                  <double>3.000000000000000</double>
                  </property>
                  <property name="singleStep">
                   <double>0.100000000000000</double>
@@ -771,7 +771,7 @@ The default pattern \[.+\]|\+ excludes tags of the form [tag], e.g., [Test book]
  <resources/>
  <connections/>
  <buttongroups>
-  <buttongroup name="cover_options_bg"/>
   <buttongroup name="merge_options_bg"/>
+  <buttongroup name="cover_options_bg"/>
  </buttongroups>
 </ui>
diff --git a/src/calibre/library/catalogs/epub_mobi.py b/src/calibre/library/catalogs/epub_mobi.py
index ea94a41227..030f5163fc 100644
--- a/src/calibre/library/catalogs/epub_mobi.py
+++ b/src/calibre/library/catalogs/epub_mobi.py
@@ -33,7 +33,7 @@ class EPUB_MOBI(CatalogPlugin):
     file_types = {'azw3', 'epub', 'mobi'}
 
     THUMB_SMALLEST = "1.0"
-    THUMB_LARGEST = "2.0"
+    THUMB_LARGEST = "3.0"
 
     cli_options = [Option('--catalog-title',  # {{{
                           default='My Books',
@@ -349,7 +349,7 @@ class EPUB_MOBI(CatalogPlugin):
                 log.warning("coercing thumb_width from '%s' to '%s'" % (opts.thumb_width, self.THUMB_LARGEST))
                 opts.thumb_width = self.THUMB_LARGEST
             opts.thumb_width = "%.2f" % float(opts.thumb_width)
-        except:
+        except Exception:
             log.error("coercing thumb_width from '%s' to '%s'" % (opts.thumb_width, self.THUMB_SMALLEST))
             opts.thumb_width = "1.0"