I have an issue for which I have a work-around solution. I'm hoping to eliminate the work-around to improve production efficiency.

My associate's server automatically runs a script that outputs a large file of research data (all text) in a json string and saves it as a huge (4MB+) .json file.

I retrieve this file via ftp. My understanding is that the ftp software (Fetch) delivers the file to me just as it was saved.

When I try to process the file contents (from Terminal) using a Python script, I receive this error:

Traceback (most recent call last):
  File "/Users/me/Documents/client drop folders/client1/pythonScript.py", line 61, in <module>
    sourceData = json.loads(line.decode("utf-8"))
UnicodeDecodeError: 'utf-8' codec can't decode byte 0xc3 in position 2547902: invalid continuation byte

The character at this position is a space — though that seems moot, considering my work-around:

My work-around is simply opening the file and resaving it (either by using VSCode's standard save dialogue OR by simply using my Mac's TextEdit and choosing to save with utf-8 character encoding and a .json extension) and overwriting the file.

The Python file processes the json with no errors after this re-saving of the source file.

If I run file -I sourceFile.json on the save before re-saving it, then it produces:

sourceFile.json: text/plain; charset=utf-8

After the re-save, the same Terminal command produces the same:

sourceFile.json: text/plain; charset=utf-8

Why would the file perform differently before and after re-saving it?

I would appreciate any knowledgeable advice or answers. Is there a better troubleshooting method than the Terminal file -I command?

Thanks in advance.


diff output:

< (entire content of file 1 from server)
\ No newline at end of file
> (entire content of file 2 saved on Mac)
\ No newline at end of file

cmp output:

old/file.json new/file.json differ: char 2547903, line 1
  • 1
    0xc3 isn't a space, it's à [which is often one of those letters that appears randomly in badly-made movie subtitles;) Space is 0x20.
    – Tetsujin
    Mar 14, 2022 at 16:16
  • 2
    It'd be interesting to see a binary compare of the files before save and after save, but basically you're having the file make a round trip through some editor that is not binary-safe (VS Code certainly is not). So the file was interpreted, and then written out again. Mar 14, 2022 at 16:39
  • 2
    The cmp shows that it does change n VSCode. Bascially the original file is not valid utf-8 iwe need to see hex dumps around char 2547903 You need to look at the task generating the file.
    – mmmmmm
    Mar 15, 2022 at 17:10
  • 1
    @MarcWilson and mmmmmm You guys must think I'm a troubleshooting n00b! I was able to get the "builder" script from the source server. As mmmmmm predicted, the script missed out running the text through php's utf8 encoder: the simple function utf8_encode Many thanks to both of you. You've steered me towards some excellent and new-to-me trouble-shooting tools here. If either of you want to post an answer, I'll swing by in a few days and approve, upvote, laud and magnify! Best.
    – Parapluie
    Mar 21, 2022 at 16:50
  • 1
    @Tetsujin Haha! Well said, though I do feel like I should be throwing alms at the feet of all those who helped. Cheers; and thanks again.
    – Parapluie
    Mar 24, 2022 at 14:12

1 Answer 1


It appears that the issue was that the source file was indeed not saved with utf-8 encoding, despite what file -I indicated. I was able to examine the php script which produced the original json output and was also able to pass the text through the php function utf8_encode to solve the problem.

If others in this forum are having similar difficulties, I highly recommend reading through the comments on the opening question, as they provide good troubleshooting tools and advice.

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