diff --git a/git_command.py b/git_command.py
index 1ec7c3ed..55216b1c 100644
--- a/git_command.py
+++ b/git_command.py
@@ -313,12 +313,15 @@ class GitCommand:
             cwd = None
         command_name = cmdv[0]
         command.append(command_name)
-        # Need to use the --progress flag for fetch/clone so output will be
-        # displayed as by default git only does progress output if stderr is a
-        # TTY.
-        if sys.stderr.isatty() and command_name in ("fetch", "clone"):
-            if "--progress" not in cmdv and "--quiet" not in cmdv:
-                command.append("--progress")
+
+        if command_name in ("fetch", "clone"):
+            env["GIT_TERMINAL_PROMPT"] = "0"
+            # Need to use the --progress flag for fetch/clone so output will be
+            # displayed as by default git only does progress output if stderr is
+            # a TTY.
+            if sys.stderr.isatty():
+                if "--progress" not in cmdv and "--quiet" not in cmdv:
+                    command.append("--progress")
         command.extend(cmdv[1:])
 
         event_log = (
diff --git a/project.py b/project.py
index dda01331..b281863b 100644
--- a/project.py
+++ b/project.py
@@ -2697,6 +2697,19 @@ class Project:
                 )
                 # Continue right away so we don't sleep as we shouldn't need to.
                 continue
+            elif (
+                ret == 128
+                and gitcmd.stdout
+                and "fatal: could not read Username" in gitcmd.stdout
+            ):
+                # User needs to be authenticated, and Git wants to prompt for
+                # username and password.
+                print(
+                    "git requires authentication, but repo cannot perform "
+                    "interactive authentication. Check git credentials.",
+                    file=output_redir,
+                )
+                break
             elif current_branch_only and is_sha1 and ret == 128:
                 # Exit code 128 means "couldn't find the ref you asked for"; if
                 # we're in sha1 mode, we just tried sync'ing from the upstream