What can be problem with encoding in PHP for some operations?
Problems arose when integrating with some services - the team json_encode returns an empty string when encoding the array in json. During debugging it turned out that part of the data in the array in the encoding ISO-8859-1.
The same happens while writing data file.
The array is formed from two sources - data from the database and the data sehardcore in the code files in UTF-8.
Two different script behave differently - in one the data that is added in code and written to a file using file_put_contents the final file in UTF-8, and the data from the database in ISO-8859-1.
Such an array while trying to retrieve the json is converted to the empty string.
In another all the data are written to the file in ISO-8859-1, and is displayed in the browser as UTF-8 and is converted into json.
That ISO-8859-1 learned after recoding on the website of Lebedev.
In the Php settings everywhere UTF-8. ISO-8859-1 generally does not appear anywhere.
Don't even know where to dig.
Tag Bitrix despite the fact that the site on Bitrix, but I think it does not matter.