Ignore HTTP500 in optional notifications

calibre-plugin/__init__.py

@@ -33,6 +33,8 @@
 #          fix ACSM files from Google Play books (no metadata node), 
 #          allow converting an anonymous auth to an AdobeID auth, 
 #          update python-cryptography from 3.4.8 to 36.0.1, update python-rsa from 4.7.2 to 4.8.
+# Currently in development: 
+#          Ignore fatal HTTP errors during optional fulfillment notifications.
 
 PLUGIN_NAME = "DeACSM"
 PLUGIN_VERSION_TUPLE = (0, 0, 15)

calibre-plugin/libadobe.py

@@ -271,7 +271,13 @@ def sendPOSTHTTPRequest(URL: str, document: bytes, type: str, returnRC = False):
     ctx.verify_mode = ssl.CERT_NONE
 
     req = urllib.request.Request(url=URL, headers=headers, data=document)
-    handler = urllib.request.urlopen(req, context=ctx)
+    try: 
+        handler = urllib.request.urlopen(req, context=ctx)
+    except urllib.error.HTTPError as err: 
+        # This happens with HTTP 500 and related errors.
+        print("Post request caused HTTPError %d" % (err.code))
+        return err.code, "Post request caused HTTPException"
+
 
     ret_code = handler.getcode()
     if (ret_code == 204 and returnRC):