TYPO3 Core

Hi,

I detect why this error-message appears:

In line 125 in file FileWriter.php is

$data = '- ' . json_encode($recordData);

Some of the items in array $recordData seem not to be utf-8.
When I write this before the json_encode, I don't get the error-message:

array_walk_recursive($recordData, function(&$item, $key){
if(!mb_detect_encoding($item, 'utf-8', true)){
$item = utf8_encode($item);
}
});

Is this the solution or is there another way without editing this file of the core by my own??

Any update here?

I updated from 6.2.14 to 6.2.19 and the error still appears and I can still fix it with the lines above.
No, I don't know where the non UTF8 chars come from - how can I check that?