Windows batch user input variable is not set within an if - windows

Question

I have a program which has following flow. Problem is the windows batch file doesn't properly checks errorlevel and doesn't set KILLSTS value. Could you please let me know what's wrong with this program and how to fix this?
Ask user to open an exe
if Yes
check exe is running or not
if running, ask user whether to close that exe
if yes close exe
run the exe
else
exit
Here is the sample batch file.
#ECHO OFF
#REM SETLOCAL ENABLEEXTENSIONS
SET /P AREYOUSURE="Open Spring STS [y/n]>"
set AREYOUSURE=%AREYOUSURE:~0,1%
ECHO AREYOUSURE=%AREYOUSURE:~0,1%
IF /I %AREYOUSURE% == N (
SET /A errno^|=%ERROR_OTHERCOMMAND_FAILED%
echo Existing Batch
EXIT /B %errno%
)
SETLOCAL
#REM SET KILLSTS=Y
tasklist /fi "IMAGENAME eq STS.exe" |find ":" > nul
ECHO Error %errorlevel%
IF %errorlevel% neq 0 (
SETLOCAL
SET /P KILLSTS="Spring STS is running. Kill STS Process [y/n]>"
echo KILLSTS %KILLSTS%
set KILLSTS=%KILLSTS:~0,1%
echo KILLSTS AFTER SUBSTR %KILLSTS%
IF /I %KILLSTS% == Y TASKKILL /f /im "STS.exe"
ENDLOCAL
)
START "" "C:\sts-bundle\sts-3.8.3.RELEASE\STS.exe"
I am getting below error

Answer 1

You need to learn how to properly format if statements.
You are formatting them as:
IF /I %KILLSTS% == Y TASKKILL /f /im "STS.exe"
When they should be formatted as:
if /i "%KILLSTS%"=="Y" (TASKKILL /f /im STS.exe)
The formatting doesn't really matter as such in simple batch files, but it's best to use the correct syntax which can handle special characters such as SPACES, AMPERSANDS, QUOTES, PIPE for when more complex variables are involved.
Updated script:
#ECHO OFF
#REM SETLOCAL ENABLEEXTENSIONS
SET /P "AREYOUSURE=Open Spring STS [y/n]>"
set "AREYOUSURE=%AREYOUSURE:~0,1% "
echo "AREYOUSURE=%AREYOUSURE:~0,1%"
IF /I "%AREYOUSURE%"=="N" (
SET /A errno^|=%ERROR_OTHERCOMMAND_FAILED%
echo Existing Batch
EXIT /B %errno%
)
SETLOCAL
#REM SET KILLSTS=Y
tasklist /fi "IMAGENAME eq STS.exe" | find ":" > nul
ECHO Error %errorlevel%
IF "%errorlevel%" neq "0" (
call :escapeexpansion
)
START "" "C:\sts-bundle\sts-3.8.3.RELEASE\STS.exe"
exit /b
:escapeexpansion
SETLOCAL
SET /P "KILLSTS=Spring STS is running. Kill STS Process [y/n]>"
echo KILLSTS %KILLSTS%
set "KILLSTS=%KILLSTS:~0,1%"
echo KILLSTS AFTER SUBSTR %KILLSTS%
IF /I "%KILLSTS%"=="Y" TASKKILL /f /im "STS.exe"
ENDLOCAL
goto :EOF

Answer 2

The entire structure seems wrong to me; as well as pointlessly using SET /P instead of CHOICE.
#ECHO OFF
TASKLIST /FI "IMAGENAME eq STS.exe"|FIND ":">NUL 2>&1&&GOTO ASKIF
CHOICE /M "Spring STS is running. Kill STS Process"
IF ERRORLEVEL 2 GOTO ENDIT
TASKKILL /F /IM "STS.exe"
TIMEOUT 3 /NOBREAK>NUL
:ASKIF
CHOICE /M "Open Spring STS"
IF ERRORLEVEL 2 GOTO ENDIT
START "" "C:\sts-bundle\sts-3.8.3.RELEASE\STS.exe"
:ENDIT
Echo=Exiting Batch
TIMEOUT 3 /NOBREAK>NUL