diff --git a/Makefile b/Makefile
index dd465a31915955..8c11d5e9a404fa 100644
--- a/Makefile
+++ b/Makefile
@@ -1355,6 +1355,7 @@ THIRD_PARTY_SOURCES += $(UNIT_TEST_DIR)/clar/clar/%
 
 CLAR_TEST_SUITES += u-ctype
 CLAR_TEST_SUITES += u-strvec
+CLAR_TEST_SUITES += u-mingw
 CLAR_TEST_PROG = $(UNIT_TEST_BIN)/unit-tests$(X)
 CLAR_TEST_OBJS = $(patsubst %,$(UNIT_TEST_DIR)/%.o,$(CLAR_TEST_SUITES))
 CLAR_TEST_OBJS += $(UNIT_TEST_DIR)/clar/clar.o
diff --git a/builtin/credential-cache.c b/builtin/credential-cache.c
index 7f733cb756e03c..3b8130d3d64f9c 100644
--- a/builtin/credential-cache.c
+++ b/builtin/credential-cache.c
@@ -23,7 +23,7 @@ static int connection_closed(int error)
 
 static int connection_fatally_broken(int error)
 {
-	return (error != ENOENT) && (error != ENETDOWN);
+	return (error != ENOENT) && (error != ENETDOWN) && (error != ECONNREFUSED);
 }
 
 #else
diff --git a/compat/mingw.c b/compat/mingw.c
index b1bd925c701ed0..cda75024767787 100644
--- a/compat/mingw.c
+++ b/compat/mingw.c
@@ -2673,6 +2673,91 @@ static inline int winsock_return(int ret)
 
 #define WINSOCK_RETURN(x) do { return winsock_return(x); } while (0)
 
+#undef strerror
+char *mingw_strerror(int errnum)
+{
+	static char buf[41] ="";
+	switch (errnum) {
+		case EWOULDBLOCK:
+			xsnprintf(buf, 41, "%s", "Operation would block");
+			break;
+		case EINPROGRESS:
+			xsnprintf(buf, 41, "%s", "Operation now in progress");
+			break;
+		case EALREADY:
+			xsnprintf(buf, 41, "%s", "Operation already in progress");
+			break;
+		case ENOTSOCK:
+			xsnprintf(buf, 41, "%s", "Socket operation on non-socket");
+			break;
+		case EDESTADDRREQ:
+			xsnprintf(buf, 41, "%s", "Destination address required");
+			break;
+		case EMSGSIZE:
+			xsnprintf(buf, 41, "%s", "Message too long");
+			break;
+		case EPROTOTYPE:
+			xsnprintf(buf, 41, "%s", "Protocol wrong type for socket");
+			break;
+		case ENOPROTOOPT:
+			xsnprintf(buf, 41, "%s", "Protocol not available");
+			break;
+		case EPROTONOSUPPORT:
+			xsnprintf(buf, 41, "%s", "Protocol not supported");
+			break;
+		case EOPNOTSUPP:
+			xsnprintf(buf, 41, "%s", "Operation not supported");
+			break;
+		case EAFNOSUPPORT:
+			xsnprintf(buf, 41, "%s", "Address family not supported by protocol");
+			break;
+		case EADDRINUSE:
+			xsnprintf(buf, 41, "%s", "Address already in use");
+			break;
+		case EADDRNOTAVAIL:
+			xsnprintf(buf, 41, "%s", "Cannot assign requested address");
+			break;
+		case ENETDOWN:
+			xsnprintf(buf, 41, "%s", "Network is down");
+			break;
+		case ENETUNREACH:
+			xsnprintf(buf, 41, "%s", "Network is unreachable");
+			break;
+		case ENETRESET:
+			xsnprintf(buf, 41, "%s", "Network dropped connection on reset");
+			break;
+		case ECONNABORTED:
+			xsnprintf(buf, 41, "%s", "Software caused connection abort");
+			break;
+		case ECONNRESET:
+			xsnprintf(buf, 41, "%s", "Connection reset by peer");
+			break;
+		case ENOBUFS:
+			xsnprintf(buf, 41, "%s", "No buffer space available");
+			break;
+		case EISCONN:
+			xsnprintf(buf, 41, "%s", "Transport endpoint is already connected");
+			break;
+		case ENOTCONN:
+			xsnprintf(buf, 41, "%s", "Transport endpoint is not connected");
+			break;
+		case ETIMEDOUT:
+			xsnprintf(buf, 41, "%s", "Connection timed out");
+			break;
+		case ECONNREFUSED:
+			xsnprintf(buf, 41, "%s", "Connection refused");
+			break;
+		case ELOOP:
+			xsnprintf(buf, 41, "%s", "Too many levels of symbolic links");
+			break;
+		case EHOSTUNREACH:
+			xsnprintf(buf, 41, "%s", "No route to host");
+			break;
+		default: return strerror(errnum);
+	}
+	return buf;
+}
+
 #undef gethostname
 int mingw_gethostname(char *name, int namelen)
 {
@@ -2710,15 +2795,6 @@ int mingw_socket(int domain, int type, int protocol)
 	ensure_socket_initialization();
 	s = WSASocket(domain, type, protocol, NULL, 0, 0);
 	if (s == INVALID_SOCKET) {
-		/*
-		 * WSAGetLastError() values are regular BSD error codes
-		 * biased by WSABASEERR.
-		 * However, strerror() does not know about networking
-		 * specific errors, which are values beginning at 38 or so.
-		 * Therefore, we choose to leave the biased error code
-		 * in errno so that _if_ someone looks up the code somewhere,
-		 * then it is at least the number that are usually listed.
-		 */
 		set_wsa_errno();
 		return -1;
 	}
diff --git a/compat/mingw.h b/compat/mingw.h
index 5c5066a668422a..b6f00b539aef9c 100644
--- a/compat/mingw.h
+++ b/compat/mingw.h
@@ -314,6 +314,11 @@ int mingw_socket(int domain, int type, int protocol);
 int mingw_connect(int sockfd, struct sockaddr *sa, size_t sz);
 #define connect mingw_connect
 
+char *mingw_strerror(int errnum);
+#ifndef _UCRT
+#define strerror mingw_strerror
+#endif
+
 int mingw_bind(int sockfd, struct sockaddr *sa, size_t sz);
 #define bind mingw_bind
 
diff --git a/t/meson.build b/t/meson.build
index fad6a3a7fbeb26..1b91eb2d1f28de 100644
--- a/t/meson.build
+++ b/t/meson.build
@@ -1,5 +1,6 @@
 clar_test_suites = [
   'unit-tests/u-ctype.c',
+  'unit-tests/u-mingw.c',
   'unit-tests/u-strvec.c',
 ]
 
diff --git a/t/t0301-credential-cache.sh b/t/t0301-credential-cache.sh
index dc30289f7539ee..586681c681c3cb 100755
--- a/t/t0301-credential-cache.sh
+++ b/t/t0301-credential-cache.sh
@@ -12,7 +12,7 @@ test -z "$NO_UNIX_SOCKETS" || {
 if test_have_prereq MINGW
 then
 	service_running=$(sc query afunix | grep "4  RUNNING")
-	test -z "$service_running" || {
+	test -n "$service_running" || {
 		skip_all='skipping credential-cache tests, unix sockets not available'
 		test_done
 	}
diff --git a/t/unit-tests/u-mingw.c b/t/unit-tests/u-mingw.c
new file mode 100644
index 00000000000000..cb74da5e793a33
--- /dev/null
+++ b/t/unit-tests/u-mingw.c
@@ -0,0 +1,72 @@
+#include "unit-test.h"
+
+#if defined(GIT_WINDOWS_NATIVE) && !defined(_UCRT)
+#undef strerror
+int errnos_contains(int);
+static int errnos [53]={
+    /* errnos in err_win_to_posix */
+    EACCES, EBUSY, EEXIST, ERANGE, EIO, ENODEV, ENXIO, ENOEXEC, EINVAL, ENOENT,
+    EPIPE, ENAMETOOLONG, ENOSYS, ENOTEMPTY, ENOSPC, EFAULT, EBADF, EPERM, EINTR,
+    E2BIG, ESPIPE, ENOMEM, EXDEV, EAGAIN, ENFILE, EMFILE, ECHILD, EROFS,
+    /* errnos only in winsock_error_to_errno */
+    EWOULDBLOCK, EINPROGRESS, EALREADY, ENOTSOCK, EDESTADDRREQ, EMSGSIZE,
+    EPROTOTYPE, ENOPROTOOPT, EPROTONOSUPPORT, EOPNOTSUPP, EAFNOSUPPORT,
+    EADDRINUSE, EADDRNOTAVAIL, ENETDOWN, ENETUNREACH, ENETRESET, ECONNABORTED,
+    ECONNRESET, ENOBUFS, EISCONN, ENOTCONN, ETIMEDOUT, ECONNREFUSED, ELOOP,
+    EHOSTUNREACH
+    };
+
+int errnos_contains(int errnum)
+{
+    for(int i=0;i<53;i++)
+	if(errnos[i]==errnum)
+	    return 1;
+    return 0;
+}
+#endif
+
+void test_mingw__no_strerror_shim_on_ucrt(void)
+{
+#if defined(GIT_WINDOWS_NATIVE) && defined(_UCRT)
+    cl_assert_(strerror != mingw_strerror,
+	"mingw_strerror is unnescessary when building against UCRT");
+#else
+    cl_skip();
+#endif
+}
+
+void test_mingw__strerror(void)
+{
+#if defined(GIT_WINDOWS_NATIVE) && !defined(_UCRT)
+    for(int i=0;i<53;i++)
+    {
+	char *crt;
+	char *mingw;
+	mingw = mingw_strerror(errnos[i]);
+	crt = strerror(errnos[i]);
+	cl_assert_(!strcasestr(mingw, "unknown error"),
+	    "mingw_strerror should know all errno values we care about");
+	if(!strcasestr(crt, "unknown error"))
+	    cl_assert_equal_s(crt,mingw);
+    }
+#else
+    cl_skip();
+#endif
+}
+
+void test_mingw__errno_translation(void)
+{
+#if defined(GIT_WINDOWS_NATIVE) && !defined(_UCRT)
+    /* GetLastError() return values are currently defined from 0 to 15841,
+    testing up to 20000 covers some room for future expansion */
+    for (int i=0;i<20000;i++)
+    {
+	if(i!=ERROR_SUCCESS)
+	    cl_assert_(errnos_contains(err_win_to_posix(i)),
+		"all err_win_to_posix return values should be tested against mingw_strerror");
+	/* ideally we'd test the same for winsock_error_to_errno, but it's static */
+    }
+#else
+    cl_skip();
+#endif
+}