diff --git a/earwigbot/wiki/copyvios/parsers.py b/earwigbot/wiki/copyvios/parsers.py
index 2b76e09..5d694aa 100644
--- a/earwigbot/wiki/copyvios/parsers.py
+++ b/earwigbot/wiki/copyvios/parsers.py
@@ -267,12 +267,12 @@ class _HTMLParser(_BaseTextParser):
 
         return "\n".join(soup.stripped_strings)
 
-    def _open(self, url):
+    def _open(self, url, **kwargs):
         """Try to read a URL. Return None if it couldn't be read."""
         opener = self._args.get("open_url")
         if not opener:
             return None
-        result = opener(url)
+        result = opener(url, **kwargs)
         return result.content if result else None
 
     def _load_from_blogspot(self, url):
@@ -280,15 +280,16 @@ class _HTMLParser(_BaseTextParser):
         match = re.search(r"'postId': '(\d+)'", self.text)
         if not match:
             return ""
-        post_id = match.groups(1)
-        url = "https://%s/feeds/posts/default/%s" % (url.netloc, post_id)
+        post_id = match.group(1)
+        url = "https://%s/feeds/posts/default/%s?" % (url.netloc, post_id)
         params = {
             "alt": "json",
             "v": "2",
             "dynamicviews": "1",
             "rewriteforssl": "true",
         }
-        raw = self._open(url + urllib.urlencode(params))
+        raw = self._open(url + urllib.urlencode(params),
+                         allow_content_types=["application/json"])
         if raw is None:
             return ""
         try:
@@ -381,4 +382,4 @@ _CONTENT_TYPES = {
 
 def get_parser(content_type):
     """Return the parser most able to handle a given content type, or None."""
-    return _CONTENT_TYPES.get(content_type.split(";", 1)[0])
+    return _CONTENT_TYPES.get(content_type)
diff --git a/earwigbot/wiki/copyvios/workers.py b/earwigbot/wiki/copyvios/workers.py
index 365abdc..fb75895 100644
--- a/earwigbot/wiki/copyvios/workers.py
+++ b/earwigbot/wiki/copyvios/workers.py
@@ -128,6 +128,7 @@ class _CopyvioWorker(object):
         try:
             response = self._opener.open(url, timeout=timeout)
         except (URLError, HTTPException, socket_error, ValueError):
+            self._logger.exception("Failed to fetch URL: %s", url)
             return None
 
         try:
@@ -136,9 +137,13 @@ class _CopyvioWorker(object):
             return None
 
         content_type = response.headers.get("Content-Type", "text/plain")
+        content_type = content_type.split(";", 1)[0]
         parser_class = get_parser(content_type)
-        if not parser_class:
+        if not parser_class and (
+                not allow_content_types or content_type not in allow_content_types):
             return None
+        if not parser_class:
+            parser_class = get_parser("text/plain")
         if size > (15 if parser_class.TYPE == "PDF" else 2) * 1024 ** 2:
             return None
 
@@ -182,7 +187,7 @@ class _CopyvioWorker(object):
         if result is None:
             return None
 
-        args = source.parser_args.copy()
+        args = source.parser_args.copy() if source.parser_args else {}
         args["open_url"] = functools.partial(self._open_url_raw, timeout=source.timeout)
         parser = result.parser_class(result.content, url=source.url, args=args)
         try:
@@ -255,6 +260,10 @@ class _CopyvioWorker(object):
             self._logger.debug("Source excluded by content parser")
             source.skipped = source.excluded = True
             source.finish_work()
+        except Exception:
+            self._logger.exception("Uncaught exception in worker")
+            source.skip()
+            source.finish_work()
         else:
             chain = MarkovChain(text) if text else None
             source.workspace.compare(source, chain)