diff --git a/mathtranslate/process_latex.py b/mathtranslate/process_latex.py
index b0e6d53..28f5fd9 100644
--- a/mathtranslate/process_latex.py
+++ b/mathtranslate/process_latex.py
@@ -490,3 +490,12 @@ def replace_function(match):
         else:
             return match.group(0)
     return pattern.sub(replace_function, latex)
+
+def remove_incompatible_packages(text):
+    incompatible_list=['axessibility','fontenc']
+    #axessibility,fontenc is incompatible with xeCJK and can be removed safely
+    #maybe more will be added
+    for package in incompatible_list:
+        pattern = re.compile(r'\\usepackage(\[[A-Za-z]*?\])?\{'+package+r'\}') 
+        text = re.sub(pattern,'',text)
+    return text
\ No newline at end of file
diff --git a/mathtranslate/translate.py b/mathtranslate/translate.py
index 7f860a2..a033061 100644
--- a/mathtranslate/translate.py
+++ b/mathtranslate/translate.py
@@ -226,6 +226,7 @@ def translate_full_latex(self, latex_original, make_complete=True, nocache=False
         if self.complete:
             print('It is a full latex document')
             latex_original, tex_begin, tex_end = process_latex.split_latex_document(latex_original, r'\begin{document}', r'\end{document}')
+            tex_begin = process_latex.remove_incompatible_packages(tex_begin)
             tex_begin = process_latex.remove_blank_lines(tex_begin)
             tex_begin = process_latex.insert_macro(tex_begin, '\\usepackage{xeCJK}\n\\usepackage{amsmath}')
         else:
diff --git a/mathtranslate/update.py b/mathtranslate/update.py
index eb34014..bda00e8 100644
--- a/mathtranslate/update.py
+++ b/mathtranslate/update.py
@@ -5,7 +5,7 @@
 def get_latest_version():
     url = 'https://pypi.org/pypi/mathtranslate/json'
 
-    with urllib.request.urlopen(url) as response:
+    with urllib.request.urlopen(url,timeout=15) as response:
         data = json.loads(response.read().decode('utf-8'))
         latest_version = data['info']['version']
 
diff --git a/mathtranslate/utils.py b/mathtranslate/utils.py
index 5504847..3897560 100644
--- a/mathtranslate/utils.py
+++ b/mathtranslate/utils.py
@@ -74,14 +74,17 @@
 
 
 def check_update(require_updated=True):
-    latest = get_latest_version()
-    updated = __version__ == latest
-    if updated:
-        print("The current mathtranslate is latest")
-    else:
-        print("The current mathtranslate is not latest, please update by `pip install --upgrade mathtranslate`")
-        if (not config.test_environment) and require_updated:
-            sys.exit()
+    try:
+        latest = get_latest_version()
+        updated = __version__ == latest
+        if updated:
+            print("The current mathtranslate is latest")
+        else:
+            print("The current mathtranslate is not latest, please update by `pip install --upgrade mathtranslate`")
+            if (not config.test_environment) and require_updated:
+                sys.exit()
+    except Exception as e:
+        print("Checking update failed, please check your network")
 
 
 def add_arguments(parser):