diff --git a/gallery_dl/__init__.py b/gallery_dl/__init__.py
index 7a9e0bee..62e96ae7 100644
--- a/gallery_dl/__init__.py
+++ b/gallery_dl/__init__.py
@@ -63,7 +63,7 @@ def main():
             browser, _, profile = args.cookies_from_browser.partition(":")
             browser, _, keyring = browser.partition("+")
             browser, _, domain = browser.partition("/")
-            if profile.startswith(":"):
+            if profile and profile[0] == ":":
                 container = profile[1:]
                 profile = None
             else:
diff --git a/gallery_dl/cookies.py b/gallery_dl/cookies.py
index 6e97f443..48316628 100644
--- a/gallery_dl/cookies.py
+++ b/gallery_dl/cookies.py
@@ -74,7 +74,8 @@ def load_cookies_firefox(profile=None, container=None, domain=None):
         cookies = [
             Cookie(
                 0, name, value, None, False,
-                domain, True if domain else False, domain.startswith("."),
+                domain, True if domain else False,
+                domain[0] == "." if domain else False,
                 path, True if path else False, secure, expires,
                 False, None, None, {},
             )
@@ -158,7 +159,8 @@ def load_cookies_chromium(browser_name, profile=None,
 
             cookies.append(Cookie(
                 0, name, value, None, False,
-                domain, True if domain else False, domain.startswith("."),
+                domain, True if domain else False,
+                domain[0] == "." if domain else False,
                 path, True if path else False, secure, expires or None,
                 False, None, None, {},
             ))
@@ -323,7 +325,8 @@ def _safari_parse_cookies_record(data, cookies, host=None):
 
     cookies.append(Cookie(
         0, name, value, None, False,
-        domain, True if domain else False, domain.startswith("."),
+        domain, True if domain else False,
+        domain[0] == "." if domain else False,
         path, True if path else False, is_secure, expiration_date,
         False, None, None, {},
     ))
diff --git a/gallery_dl/extractor/deviantart.py b/gallery_dl/extractor/deviantart.py
index 3b10a8b1..693def99 100644
--- a/gallery_dl/extractor/deviantart.py
+++ b/gallery_dl/extractor/deviantart.py
@@ -401,7 +401,7 @@ class DeviantartExtractor(Extractor):
         html = content["html"]
         markup = html["markup"]
 
-        if not markup.startswith("{"):
+        if not markup or markup[0] != "{":
             return markup
 
         if html["type"] == "tiptap":
diff --git a/gallery_dl/extractor/exhentai.py b/gallery_dl/extractor/exhentai.py
index 01af7a4c..3e6d5378 100644
--- a/gallery_dl/extractor/exhentai.py
+++ b/gallery_dl/extractor/exhentai.py
@@ -260,9 +260,9 @@ class ExhentaiGalleryExtractor(ExhentaiExtractor):
             "torrentcount" : extr('>Torrent Download (', ')'),
         }
 
-        if data["uploader"].startswith("<"):
-            data["uploader"] = text.unescape(text.extr(
-                data["uploader"], ">", "<"))
+        uploader = data["uploader"]
+        if uploader and uploader[0] == "<":
+            data["uploader"] = text.unescape(text.extr(uploader, ">", "<"))
 
         f = data["favorites"][0]
         if f == "N":
diff --git a/gallery_dl/extractor/foolfuuka.py b/gallery_dl/extractor/foolfuuka.py
index 85dd8969..44c4542b 100644
--- a/gallery_dl/extractor/foolfuuka.py
+++ b/gallery_dl/extractor/foolfuuka.py
@@ -37,7 +37,7 @@ class FoolfuukaExtractor(BaseExtractor):
 
             if not url and "remote_media_link" in media:
                 url = self.remote(media)
-            if url.startswith("/"):
+            if url and url[0] == "/":
                 url = self.root + url
 
             post["filename"], _, post["extension"] = \
diff --git a/gallery_dl/extractor/mangakakalot.py b/gallery_dl/extractor/mangakakalot.py
index 0183b25f..9fc8681d 100644
--- a/gallery_dl/extractor/mangakakalot.py
+++ b/gallery_dl/extractor/mangakakalot.py
@@ -19,7 +19,7 @@ BASE_PATTERN = r"(?:https?://)?(?:ww[\dw]?\.)?mangakakalot\.tv"
 class MangakakalotBase():
     """Base class for mangakakalot extractors"""
     category = "mangakakalot"
-    root = "https://ww6.mangakakalot.tv"
+    root = "https://ww8.mangakakalot.tv"
 
 
 class MangakakalotChapterExtractor(MangakakalotBase, ChapterExtractor):
@@ -40,7 +40,7 @@ class MangakakalotChapterExtractor(MangakakalotBase, ChapterExtractor):
         match = re.match(
             r"(?:[Vv]ol\. *(\d+) )?"
             r"[Cc]hapter *([^:]*)"
-            r"(?:: *(.+))?", info)
+            r"(?:: *(.+))?", info or "")
         volume, chapter, title = match.groups() if match else ("", "", info)
         chapter, sep, minor = chapter.partition(".")
 
@@ -86,7 +86,7 @@ class MangakakalotMangaExtractor(MangakakalotBase, MangaExtractor):
             data["chapter"] = text.parse_int(chapter)
             data["chapter_minor"] = sep + minor
 
-            if url.startswith("/"):
+            if url[0] == "/":
                 url = self.root + url
             results.append((url, data.copy()))
         return results
diff --git a/gallery_dl/extractor/postmill.py b/gallery_dl/extractor/postmill.py
index 29b351ba..88771758 100644
--- a/gallery_dl/extractor/postmill.py
+++ b/gallery_dl/extractor/postmill.py
@@ -50,7 +50,7 @@ class PostmillExtractor(BaseExtractor):
             forum = match.group(1)
             id = int(match.group(2))
 
-            is_text_post = url.startswith("/")
+            is_text_post = (url[0] == "/")
             is_image_post = self._search_image_tag(page) is not None
             data = {
                 "title": title,
diff --git a/gallery_dl/extractor/telegraph.py b/gallery_dl/extractor/telegraph.py
index dd5988f8..468840b2 100644
--- a/gallery_dl/extractor/telegraph.py
+++ b/gallery_dl/extractor/telegraph.py
@@ -49,7 +49,7 @@ class TelegraphGalleryExtractor(GalleryExtractor):
             url, pos = text.extract(figure, 'src="', '"')
             if url.startswith("/embed/"):
                 continue
-            elif url.startswith("/"):
+            elif url[0] == "/":
                 url = self.root + url
             caption, pos = text.extract(figure, "<figcaption>", "<", pos)
             num += 1
diff --git a/gallery_dl/extractor/tsumino.py b/gallery_dl/extractor/tsumino.py
index bce661a5..b196aeb4 100644
--- a/gallery_dl/extractor/tsumino.py
+++ b/gallery_dl/extractor/tsumino.py
@@ -148,8 +148,10 @@ class TsuminoSearchExtractor(TsuminoBase, Extractor):
             data["PageNumber"] += 1
 
     def _parse(self, query):
+        if not query:
+            return {}
         try:
-            if query.startswith("?"):
+            if query[0] == "?":
                 return self._parse_simple(query)
             return self._parse_jsurl(query)
         except Exception as exc:
@@ -187,8 +189,6 @@ class TsuminoSearchExtractor(TsuminoBase, Extractor):
         Example: ~(name~'John*20Doe~age~42~children~(~'Mary~'Bill))
         Ref: https://github.com/Sage/jsurl
         """
-        if not data:
-            return {}
         i = 0
         imax = len(data)
 
diff --git a/gallery_dl/util.py b/gallery_dl/util.py
index a269a2b6..80c53cb8 100644
--- a/gallery_dl/util.py
+++ b/gallery_dl/util.py
@@ -432,7 +432,7 @@ def cookiestxt_load(fp):
             None, False,
             domain,
             domain_specified == "TRUE",
-            domain.startswith("."),
+            domain[0] == "." if domain else False,
             path, False,
             secure == "TRUE",
             None if expires == "0" or not expires else expires,
@@ -458,9 +458,10 @@ def cookiestxt_store(fp, cookies):
             name = cookie.name
             value = cookie.value
 
+        domain = cookie.domain
         write("\t".join((
-            cookie.domain,
-            "TRUE" if cookie.domain.startswith(".") else "FALSE",
+            domain,
+            "TRUE" if domain and domain[0] == "." else "FALSE",
             cookie.path,
             "TRUE" if cookie.secure else "FALSE",
             "0" if cookie.expires is None else str(cookie.expires),