diff --git a/acme.sh b/acme.sh
index 42d94f79..d3e364bb 100755
--- a/acme.sh
+++ b/acme.sh
@@ -6658,8 +6658,10 @@ _install_win_taskscheduler() {
   _info "$PROJECT_NAME will not save your password."
   _info "Please input your Windows password for: $(__green "$_myname")"
   _password="$(__read_password)"
-  #SCHTASKS.exe '/create' '/SC' 'DAILY' '/TN' "$_WINDOWS_SCHEDULER_NAME" '/F' '/ST' "00:$_randomminute" '/RU' "$_myname" '/RP' "$_password" '/TR' "$_winbash -l -c '$_lesh --cron --home \"$LE_WORKING_DIR\" $_centry'" >/dev/null
-  echo SCHTASKS.exe '/create' '/SC' 'DAILY' '/TN' "$_WINDOWS_SCHEDULER_NAME" '/F' '/ST' "00:$_randomminute" '/RU' "$_myname" '/RP' "$_password" '/TR' "\"$_winbash -l -c '$_lesh --cron --home \"$LE_WORKING_DIR\" $_centry'\"" | cmd.exe >/dev/null
+  #schtasks.exe /ST requires the HH:mm format, so the minute must be zero-padded (issue 4950)
+  _st_minute="$(printf "%02d" "$_randomminute")"
+  #SCHTASKS.exe '/create' '/SC' 'DAILY' '/TN' "$_WINDOWS_SCHEDULER_NAME" '/F' '/ST' "00:$_st_minute" '/RU' "$_myname" '/RP' "$_password" '/TR' "$_winbash -l -c '$_lesh --cron --home \"$LE_WORKING_DIR\" $_centry'" >/dev/null
+  echo SCHTASKS.exe '/create' '/SC' 'DAILY' '/TN' "$_WINDOWS_SCHEDULER_NAME" '/F' '/ST' "00:$_st_minute" '/RU' "$_myname" '/RP' "$_password" '/TR' "\"$_winbash -l -c '$_lesh --cron --home \"$LE_WORKING_DIR\" $_centry'\"" | cmd.exe >/dev/null
   echo
 
 }