diff -Nur mitmproxy-7.0.0/mitmproxy/contentviews/__init__.py mitmproxy-7.0.0-1/mitmproxy/contentviews/__init__.py
--- mitmproxy-7.0.0/mitmproxy/contentviews/__init__.py	2021-07-16 16:24:38.000000000 +0800
+++ mitmproxy-7.0.0-1/mitmproxy/contentviews/__init__.py	2021-08-04 15:27:39.221691053 +0800
@@ -99,8 +99,10 @@
     http_message = None
     if isinstance(message, http.Message):
         http_message = message
-        if ctype := message.headers.get("content-type"):
-            if ct := http.parse_content_type(ctype):
+        ctype_tmp = message.headers.get("content-type")
+        if ctype == ctype_tmp:
+            ct_tmp = http.parse_content_type(ctype)
+            if ct == ct_tmp:
                 content_type = f"{ct[0]}/{ct[1]}"
 
     description, lines, error = get_content_view(
diff -Nur mitmproxy-7.0.0/mitmproxy/net/tls.py mitmproxy-7.0.0-1/mitmproxy/net/tls.py
--- mitmproxy-7.0.0/mitmproxy/net/tls.py	2021-07-16 16:24:38.000000000 +0800
+++ mitmproxy-7.0.0-1/mitmproxy/net/tls.py	2021-08-04 15:32:53.086778204 +0800
@@ -106,7 +106,7 @@
     ok += SSL._lib.SSL_CTX_set_max_proto_version(context._context, max_version.value)  # type: ignore
     if ok != 2:
         raise RuntimeError(
-            f"Error setting TLS versions ({min_version=}, {max_version=}). "
+            f"Error setting TLS versions ({min_version}, {max_version}). "
             "The version you specified may be unavailable in your libssl."
         )
 
@@ -177,7 +177,7 @@
     try:
         context.load_verify_locations(ca_pemfile, ca_path)
     except SSL.Error as e:
-        raise RuntimeError(f"Cannot load trusted certificates ({ca_pemfile=}, {ca_path=}).") from e
+        raise RuntimeError(f"Cannot load trusted certificates ({ca_pemfile}, {ca_path}).") from e
 
     # Client Certs
     if client_cert:
diff -Nur mitmproxy-7.0.0/mitmproxy/proxy/layers/http/__init__.py mitmproxy-7.0.0-1/mitmproxy/proxy/layers/http/__init__.py
--- mitmproxy-7.0.0/mitmproxy/proxy/layers/http/__init__.py	2021-07-16 16:24:38.000000000 +0800
+++ mitmproxy-7.0.0-1/mitmproxy/proxy/layers/http/__init__.py	2021-08-04 15:30:16.424239006 +0800
@@ -148,8 +148,8 @@
         else:
             self.flow = event.replay_flow
         self.flow.request = event.request
-
-        if err := validate_request(self.mode, self.flow.request):
+        err_tmp = validate_request(self.mode, self.flow.request)
+        if err == err_tmp:
             self.flow.response = http.Response.make(502, str(err))
             self.client_state = self.state_errored
             return (yield from self.send_response())
diff -Nur mitmproxy-7.0.0/mitmproxy/proxy/server.py mitmproxy-7.0.0-1/mitmproxy/proxy/server.py
--- mitmproxy-7.0.0/mitmproxy/proxy/server.py	2021-07-16 16:24:38.000000000 +0800
+++ mitmproxy-7.0.0-1/mitmproxy/proxy/server.py	2021-08-04 15:31:48.925738277 +0800
@@ -142,7 +142,8 @@
             server=command.connection
         )
         await self.handle_hook(server_hooks.ServerConnectHook(hook_data))
-        if err := command.connection.error:
+        err_tmp = command.connection.error
+        if err == err_tmp:
             self.log(f"server connection to {human.format_address(command.connection.address)} killed before connect: {err}")
             self.server_event(events.OpenConnectionCompleted(command, f"Connection killed: {err}"))
             return