Warning Error with json_encode()

[katmoody]

User in forums reported the following error:
[10-May-2017 04:20:57 UTC] PHP Warning: json_encode() [function.json-encode]: Invalid UTF-8 sequence in argument in /home/www/…./wp-content/plugins/backupwordpress/classes/class-site-size.php on line 156

Which traces back to this part of the plugin code: https://github.com/humanmade/backupwordpress/blob/master/classes/class-site-size.php#L156

It looks like the json_encode() value has to be UTF-8 encoded per the PHP manual:
http://php.net/manual/en/function.json-encode.php

And further discussed in this Stack Overflow post:
http://stackoverflow.com/questions/10205722/json-encode-invalid-utf-8-sequence-in-argument

Link to forum post: https://wordpress.org/support/topic/utf-warning-on-utf-8/#post-9117239

[katmoody]

It looks like one solution might be to add the UTF-8 encoding where other parts of the function are defined: https://github.com/humanmade/backupwordpress/blob/46df3a749cc8a77d3de724f0f63c44b6e5d2c5eb/classes/backup/class-backup-engine-database-imysqldump.php#L27

I think it's only happening when using the PDO option that is part of the IMySQLDump (the php version) so resolving this should solve this warning? Unless I misunderstood where the value could be added?

[roborourke]

Not sure the mysql dump classes are related here as the offending warning comes from a line in the directory file size calculation methods.