diff --git a/src/cmd/commands.cpp b/src/cmd/commands.cpp
index b4b1ad3..0de43c8 100644
--- a/src/cmd/commands.cpp
+++ b/src/cmd/commands.cpp
@@ -13,7 +13,9 @@ namespace mob
 
 BOOL WINAPI signal_handler(DWORD) noexcept
 {
-	gcx().debug(context::generic, "caught sigint");
+	// don't use u8cout, this would lock the global mutex, but the handler
+	// can be called while stuff is being output and the mutex is locked
+	std::wcout << L"sigint, interrupting...\n";
 	task_manager::instance().interrupt_all();
 	return TRUE;
 }
diff --git a/src/cmd/pr.cpp b/src/cmd/pr.cpp
index ea33a1c..5f56957 100644
--- a/src/cmd/pr.cpp
+++ b/src/cmd/pr.cpp
@@ -397,7 +397,7 @@ std::vector<pr_command::pr_info> pr_command::validate_prs(
 			return {};
 		}
 
-		if (!ask_yes_no("these prs will be ignored; proceed anyway?", false))
+		if (ask_yes_no("these prs will be ignored; proceed anyway?", yn::no) != yn::yes)
 			return {};
 
 		u8cout << "\n";
diff --git a/src/cmd/release.cpp b/src/cmd/release.cpp
index f2994b2..9aa0cbd 100644
--- a/src/cmd/release.cpp
+++ b/src/cmd/release.cpp
@@ -4,6 +4,7 @@
 #include "../core/conf.h"
 #include "../core/context.h"
 #include "../core/op.h"
+#include "../core/ini.h"
 #include "../tasks/tasks.h"
 #include "../tasks/task_manager.h"
 #include "../utility/threading.h"
@@ -360,21 +361,45 @@ bool release_command::check_clean_prefix()
 	if (!fs::exists(prefix))
 		return true;
 
-	u8cout
-		<< "prefix " << path_to_utf8(prefix) << " already exists\n"
-		<< "delete? [Y/n] ";
+	bool saw_file = false;
+	const fs::path log_file = conf().global().get("log_file");
+	const std::string ini_file = default_ini_filename();
 
-	std::wstring s;
-	std::getline(std::wcin, s);
-
-	if (s == L"" || s == L"y" || s == L"Y")
+	for (auto itor : fs::directory_iterator(prefix))
 	{
-		build_command::terminate_msbuild();
-		op::delete_directory(gcx(), prefix);
+		const auto name = itor.path().filename();
+
+		// ignore ini and logs
+		if (name == log_file.filename() || name == ini_file)
+			continue;
+
+		saw_file = true;
+		break;
+	}
+
+	if (!saw_file)
+	{
+		// empty directory, that's fine
 		return true;
 	}
 
-	return false;
+	const auto q = fmt::format(
+		"prefix {} already exists, delete?", path_to_utf8(prefix));
+
+	if (ask_yes_no(q, yn::no) != yn::yes)
+		return false;
+
+	// the log file might be in this directory, close it now and reopen it
+	// when deletion is finished
+	context::close_log_file();
+
+	build_command::terminate_msbuild();
+	op::delete_directory(gcx(), prefix);
+
+	// reopen log file
+	conf().set_log_file();
+
+	return true;
 }
 
 void release_command::prepare()
diff --git a/src/core/conf.cpp b/src/core/conf.cpp
index fb20f92..dee8b19 100644
--- a/src/core/conf.cpp
+++ b/src/core/conf.cpp
@@ -401,6 +401,13 @@ void process_option(
 
 			// task must exist
 			const auto& tasks = task_manager::instance().find(task);
+
+			if (tasks.empty())
+			{
+				gcx().bail_out(context::conf,
+					"bad option {}, task '{}' not found", section_string, task);
+			}
+
 			MOB_ASSERT(!tasks.empty());
 
 			for (auto& t : tasks)
@@ -522,6 +529,14 @@ void resolve_paths()
 	details::set_string("tools", "iscc", path_to_utf8(find_iscc()));
 }
 
+void conf::set_log_file()
+{
+	// set up the log file, resolve against prefix if relative
+	fs::path log_file = conf().global().get("log_file");
+	if (log_file.is_relative())
+		log_file = conf().path().prefix() / log_file;
+}
+
 void init_options(
 	const std::vector<fs::path>& inis, const std::vector<std::string>& opts)
 {
@@ -596,11 +611,7 @@ void init_options(
 		resolve_path("prefix", prefix_root, "");
 
 	// set up the log file, resolve against prefix if relative
-	fs::path log_file = conf().global().get("log_file");
-	if (log_file.is_relative())
-		log_file = conf().path().prefix() / log_file;
-
-	context::set_log_file(log_file);
+	conf().set_log_file();
 
 	// goes through all paths and tools, finds missing or relative stuff, bails
 	// out of stuff can't be found
diff --git a/src/core/conf.h b/src/core/conf.h
index 0dd82b7..2bd1e0e 100644
--- a/src/core/conf.h
+++ b/src/core/conf.h
@@ -242,6 +242,10 @@ public:
 	conf_prebuilt prebuilt();
 	conf_versions version();
 	conf_paths path();
+
+	// opens the log file, creates the directory if needed
+	//
+	void set_log_file();
 };
 
 }	// namespace
diff --git a/src/core/context.cpp b/src/core/context.cpp
index efe9a6d..a628820 100644
--- a/src/core/context.cpp
+++ b/src/core/context.cpp
@@ -248,6 +248,11 @@ void context::set_log_file(const fs::path& p)
 	}
 }
 
+void context::close_log_file()
+{
+	g_log_file.reset();
+}
+
 void context::log_string(reason r, level lv, std::string_view s) const
 {
 	if (!enabled(lv))
diff --git a/src/core/context.h b/src/core/context.h
index 4306dad..6a38141 100644
--- a/src/core/context.h
+++ b/src/core/context.h
@@ -148,6 +148,10 @@ public:
 	//
 	static void set_log_file(const fs::path& p);
 
+	// closes the output file for logs, see release_command::check_clean_prefix()
+	//
+	static void close_log_file();
+
 
 	// creates a context for a task; the global context has no name
 	//
diff --git a/src/core/ini.h b/src/core/ini.h
index 2130b60..4957078 100644
--- a/src/core/ini.h
+++ b/src/core/ini.h
@@ -27,5 +27,6 @@ struct ini_data
 };
 
 ini_data parse_ini(const fs::path& ini);
+std::string default_ini_filename();
 
 }	// namespace
diff --git a/src/utility/assert.cpp b/src/utility/assert.cpp
index 8434ace..96c2501 100644
--- a/src/utility/assert.cpp
+++ b/src/utility/assert.cpp
@@ -9,21 +9,23 @@ void mob_assertion_failed(
   const char* message,
   const char* exp, const wchar_t* file, int line, const char* func)
 {
-  if (message)
-  {
-	gcx().error(context::generic,
-	  "assertion failed: {}:{} {}: {} ({})",
-	  std::wstring(file), line, func, message, exp);
-  }
-  else
-  {
-	gcx().error(context::generic,
-	  "assertion failed: {}:{} {}: '{}'",
-	  std::wstring(file), line, func, exp);
-  }
+	if (message)
+	{
+		gcx().error(context::generic,
+			"assertion failed: {}:{} {}: {} ({})",
+			std::wstring(file), line, func, message, exp);
+	}
+	else
+	{
+		gcx().error(context::generic,
+			"assertion failed: {}:{} {}: '{}'",
+			std::wstring(file), line, func, exp);
+	}
 
-  if (IsDebuggerPresent())
-	DebugBreak();
+	if (IsDebuggerPresent())
+		DebugBreak();
+	else
+		std::exit(1);
 }
 
 } // namespace
diff --git a/src/utility/io.cpp b/src/utility/io.cpp
index dd9304c..9ff3c2f 100644
--- a/src/utility/io.cpp
+++ b/src/utility/io.cpp
@@ -81,65 +81,71 @@ std::mutex& global_output_mutex()
   return g_output_mutex;
 }
 
-bool ask_yes_no(const std::string& text, bool def)
+yn ask_yes_no(const std::string& text, yn def)
 {
 	u8cout
 		<< text
 		<< (text.empty() ? "" : " ")
-		<< (def ? "[Y/n]" : "[y/N]")
+		<< (def == yn::yes ? "[Y/n]" : "[y/N]")
 		<< " ";
 
 	// stdin is not utf8
 	std::string line;
 	std::getline(std::cin, line);
 
+	// ctrl+c
+	if (!std::cin)
+		return yn::cancelled;
+
 	if (line.empty())
 		return def;
 	else if (line == "y" || line == "Y")
-		return true;
+		return yn::yes;
+	else if (line == "n" || line == "N")
+		return yn::no;
 	else
-		return false;
+		return yn::cancelled;
 }
 
 
 void u8stream::do_output(const std::string& s)
 {
-  std::scoped_lock lock(g_output_mutex);
+	std::scoped_lock lock(g_output_mutex);
 
-  if (err_)
-  {
-	if (stderr_console)
-	  std::wcerr << utf8_to_utf16(s);
+	if (err_)
+	{
+		if (stderr_console)
+			std::wcerr << utf8_to_utf16(s);
+		else
+			std::cerr << s;
+	}
 	else
-	  std::cerr << s;
-  }
-  else
-  {
-	if (stdout_console)
-	  std::wcout << utf8_to_utf16(s);
-	else
-	  std::cout << s;
-  }
+	{
+		if (stdout_console)
+			std::wcout << utf8_to_utf16(s);
+		else
+			std::cout << s;
+	}
 }
 
 void u8stream::write_ln(std::string_view utf8)
 {
-  std::scoped_lock lock(g_output_mutex);
+	std::scoped_lock lock(g_output_mutex);
 
-  if (err_)
-  {
-	if (stderr_console)
-	  std::wcerr << utf8_to_utf16(utf8) << L"\n";
+	if (err_)
+	{
+		if (stderr_console)
+			std::wcerr << utf8_to_utf16(utf8) << L"\n";
+		else
+			std::cerr << utf8 << "\n";
+	}
 	else
-	  std::cerr << utf8 << "\n";
-  }
-  else
-  {
-	if (stdout_console)
-	  std::wcout << utf8_to_utf16(utf8) << L"\n";
-	else
-	  std::cout << utf8 << "\n";
-  }
+	{
+		if (stdout_console)
+			std::wcout << utf8_to_utf16(utf8) << L"\n";
+		else
+			std::cout << utf8 << "\n";
+	}
 }
 
 
diff --git a/src/utility/io.h b/src/utility/io.h
index c3c6b80..2f21a5d 100644
--- a/src/utility/io.h
+++ b/src/utility/io.h
@@ -102,9 +102,17 @@ void set_std_streams();
 //
 std::mutex& global_output_mutex();
 
+
+enum class yn
+{
+	no = 0,
+	yes,
+	cancelled
+};
+
 // asks the user for y/n
 //
-bool ask_yes_no(const std::string& text, bool def);
+yn ask_yes_no(const std::string& text, yn def);
 
 
 // see https://github.com/isanae/mob/issues/4
diff --git a/src/utility/threading.cpp b/src/utility/threading.cpp
index 61dd029..6a4d2b1 100644
--- a/src/utility/threading.cpp
+++ b/src/utility/threading.cpp
@@ -19,9 +19,9 @@ static LPTOP_LEVEL_EXCEPTION_FILTER g_previous_handler = nullptr;
 
 void dump_stacktrace(const wchar_t* what)
 {
-	std::scoped_lock lock(global_output_mutex());
-
-	std::wcerr
+	// don't use 8ucout, don't lock the global out mutex, this can be called
+	// while the mutex is locked
+	std::wcerr << what
 		<< "\n\nmob has crashed\n"
 		<< L"*****************************\n\n"
 		<< what << L"\n\n";