import re
s = "Example=N ; Comment Line One error=\n\n; Comment Line Two.\n\nDesired=\n"
config_value = 'Example'
pattern=r'(?sm)^{}=(.*?)(?=[\r\n]+\w+=|\Z)'.format(config_value)
match = re.search(pattern, s)
if match:
print(match.group(1))
aW1wb3J0IHJlCnMgPSAiRXhhbXBsZT1OICAgICAgOyBDb21tZW50IExpbmUgT25lIGVycm9yPVxuXG47IENvbW1lbnQgTGluZSBUd28uXG5cbkRlc2lyZWQ9XG4iCmNvbmZpZ192YWx1ZSA9ICdFeGFtcGxlJwpwYXR0ZXJuPXInKD9zbSlee309KC4qPykoPz1bXHJcbl0rXHcrPXxcWiknLmZvcm1hdChjb25maWdfdmFsdWUpCm1hdGNoID0gcmUuc2VhcmNoKHBhdHRlcm4sIHMpCmlmIG1hdGNoOgogICAgcHJpbnQobWF0Y2guZ3JvdXAoMSkp