Maybe someting related to twig issue only.

Did you update twig config ? (it can bne done by plugins or via config.php file).
Can you activate debug mode ?

I don't think «Did you mean "json_decode"?» is added by PHP

Can you activate debug mode ?

Ok,I try debug mode to find more informations

Do i ask a question

How to update twig config?

I po Stack Trace error

1.LimeSurvey 3.5.0\application\third_party\Twig\ExpressionParser.php(374): Twig_ExpressionParser->getFunctionNodeClass("json_encode", 52)
369
370 return $node;
371 }
372
373 $args = $this->parseArguments(true);
374 $class = $this->getFunctionNodeClass($name, $line);
375
376 return new $class($name, $args, $line);
377 }
378 }
379

2.LimeSurvey 3.5.0\application\third_party\Twig\ExpressionParser.php(162): Twig_ExpressionParser->getFunctionNode("json_encode", 52)
157 $node = new Twig_Node_Expression_Constant(null, $token->getLine());
158 break;
159
160 default:
161 if ('(' === $this->parser->getCurrentToken()->getValue()) {
162 $node = $this->getFunctionNode($token->getValue(), $token->getLine());
163 } else {
164 $node = new Twig_Node_Expression_Name($token->getValue(), $token->getLine());
165 }
166 }
167 break;

3. LimeSurvey 3.5.0\application\third_party\Twig\ExpressionParser.php(102): Twig_ExpressionParser->parsePrimaryExpression()
097 $this->parser->getStream()->expect(Twig_Token::PUNCTUATION_TYPE, ')', 'An opened parenthesis is not properly closed');
098
099 return $this->parsePostfixExpression($expr);
100 }
101
102 return $this->parsePrimaryExpression();
103 }
104
105 protected function parseConditionalExpression($expr)
106 {
107 while ($this->parser->getStream()->nextIf(Twig_Token::PUNCTUATION_TYPE, '?')) {

Tomorrow, i will try

1. how to update twig

2.update to new version limesurvey

Hi

I try to po some # to code

filename: answer.twig

{# Set option for launch, can not set to default : maybe more than one datetimepicker in page #}
{# get the same default value than qanda_helper #}
{#% set aJsonOption = json_encode({#
#'format' : dateformatdetailsjs,#
#'minDate' : mindate[0] == '{' ? '2018-01-01' : mindate,#
#'maxDate' : maxdate[0] == '{' ? '2037-12-31' : maxdate,#
#'sideBySide' : true#
# })#
#%#}

I view survey,datepick can show

BUT i finish survey, it show:[Could not convert date 11/19/2018 1:49 PM to format d.m.Y. Please check your date format settings.]

Update to last version …

thank you