Why Excel thinks your CSV is a SYLK

Just a quick post to share a tip I discovered this morning. I was generating a CSV file and for some reason when I went to open it in Excel, I got a message saying the file’s extension was CSV, but the file format was SYLK. Clicking through a couple message boxes opened the file up just fine anyway.

A bit of digging turned up the Wikipedia page linked above, and within it the format syntax description:

”’ID”’ record:
A header to identify spreadsheet type and creator.
Must be first record in the file.

Yep. If the first record of your CSV file is “ID”, Excel will attempt to intepret the file as SYLK. Changing “ID” to anything else (including “Id” or “id”) fixes the issue.

Leave a comment


  1. WarrenP

     /  April 25, 2011

    That’s hilarious. Too bad you can’t just go on the Excel project’s sourceforge page and post a bug. 🙂


  2. Doug Carr

     /  December 5, 2011

    That is just crazy. Thanks again Microsoft for thinking that your software is smarter than it really is.

    I just ran into this issue and your tip solved the issue right away.

    I thank you so very much for posting this.


  3. thebitguru

     /  March 21, 2012

    That dialog was annoying, thanks for posting the solution and the reasoning behind it!

  4. jessamin

     /  May 24, 2012

    I love that I just entered “why excel thinks csv” into google and it autocompleted with sylk. Thank you for posting this solution!

  5. Most helpful, thanks for posting. I was flummoxed by this until I searched and found this post.

  6. Just arrived here through a Google search. Thanks a lot for your post, it’s solved my problem.

    Crazy behaviour in Excel though. Surely checking for a .slk extension would be enough rather than assuming that your .csv must just be wrong? Even just opening as a CSV if the first column name is ‘ID’, the extension is .csv and the SYLK check failed would be better.

  7. Anna – Thank you for saving me a lot of time!

  8. Brian B

     /  December 3, 2013

    Just wanted to add my thanks to the others above. I had the same experience as jessamin — I Googled “excel thinks csv is”, it filled in SYLK and up popped your post and the solution! Perfect…. THANKS!

  9. Eric

     /  January 22, 2014

    You saved my day – thank you!
    Greetings, Eric
    PS: Found you by searching “excel csv sylk” at google (position: 3)

  10. Alex B

     /  May 9, 2014

    Thanks so much. A bit more detail: Excel will mess this up not only if the field name is ‘ID’, but also if the field name ends with ID, such as ‘messageID’.

  11. Thank you for the tip!

  12. Add me to the list of “huh?!” and “thanks!”

  13. Thanks a lot Anna! You saved my day (s)!
    Just to add:when you try to open a CSV file you just saved from Excel itself, it fails! How could a software do such stupid things ?

  14. Sven Berkvens-Matthijsse

     /  September 25, 2014

    Thanks very much, just ran into this and your explanation saved me a whole lot of time 🙂

  15. Dave Patterson

     /  January 19, 2015

    Thanks for posting this. So glad it turned up first in my search for how to solve this annoying problem.

  16. Ki Hulme

     /  January 30, 2015

    Many thanks for the post. And thanks Microsoft for more none-sense.

  17. Bastien

     /  February 13, 2015

    Many thanks for these explanations on another great functionality of a Microsoft software.

  18. marcus

     /  May 13, 2015

    Fab tip, thanks for that!

  19. This posting saved a significant amount of head scratching!! Thanks.

  20. fogbear

     /  July 22, 2015

    Wow! More than five years later, and this post is still generating responses. It’s one of those eternal Microsoft annoyances that I just ignored for years until I finally decided to try to find an answer.

  21. Thanks so much! I was wondering about that.

  22. praflo

     /  August 16, 2015

    Thank you Anna. This saved me some time.

  23. Taibe

     /  September 20, 2015

    Thank you so much. I don’t know how I’d ever have figured out what was wrong without your post.

  24. jrw

     /  September 25, 2015

    Still a bug in Excel 2013

  25. Eternal gratitude for this post.

  26. Roger Fitch

     /  November 27, 2015

    Great thanks,sorted 🙂

  27. Ricard

     /  November 29, 2015

    Very Useful. Adding to Alex B comment, in my case Excel was also confused by a first field called IDPatient.

  28. Eric James Stone

     /  January 18, 2016

    Thanks for posting this solution. I was mystified as to what I was doing wrong with my CSV format.

  29. Brian

     /  January 19, 2016

    Confirmed still a bug in Excel 2016

  30. Noud van Klinken

     /  February 10, 2016

    Thanks Anne!

  31. Piskvor

     /  March 8, 2016

    Wonderful. Thanks!

    If you absolutely *need* to have “ID” in the first column, consider ” ID”, or worse, =”ID”
    The latter one is technically Excel syntax, not CSV, but Excel will parse it as its string anyway. Weird stuff.

  32. Thank you! Saved my evening if not more.

  33. Kroh

     /  March 8, 2016

    Wow, can’t thank you enough for posting this solution! Couldn’t figure out why csv files as output were fine sometimes and were interpreted as SYLK files in other cases. You saved me HOURS of head banging!

  34. Frank SanPietro

     /  March 24, 2016

    Many Thanks. Found you via Google search and the tip prevented me from redoing a bunch of work. Echo the frustration of others re: why MS has to “overthink” things sometimes. Thanks again.

  35. Ghislain

     /  August 9, 2016

    You make my day !!!

  36. steinar

     /  September 9, 2016

    2016 – thank you!!


  37. So I’m not the only person encountering this problem today. Hilarious.

  38. hoshantm

     /  October 10, 2016

    Thanks! You helped me resolved this problem in a minimal amount of time.

  39. Malcolm Farrelle

     /  November 25, 2016

    Like others – thanks so much. Now if you could tell me why my C200 Doesn’t start 1 time in 12 I’d be super-impressed!

  40. Liam S Kelly

     /  November 28, 2016

    Thanks Anna,

    This has been annoying me for over a week. Applied you fix – sorted in seconds. Still a bug in Excel 2016

  41. Cool thanks for the post!!

  42. Darryl_G

     /  January 10, 2017

    Awesome! Thanks Anna for helping us quickly solve this mystery! 🙂
    Thanks Microsoft for keeping things interesting! 😐

  43. Asko

     /  January 25, 2017


  44. gReG

     /  February 22, 2017

    Just to let you know I am yet another person helped by your post. Thanks for taking the time to post it. The gift that keeps on giving…. 🙂

  45. Ingo

     /  March 22, 2017

    Thanks for your post, still valid after seven years! Ran into the problem, googled SYLK and found a lot of pages advertising intimate moisturiser. 😀 Adding “Excel” to the search terms brought me here to enlightenment.

  46. Holden Hackbarth

     /  May 5, 2017

    An amazing coincidence, just ran into this problem myself. Thanks for your post, fixed the issue…

  47. Dan

     /  June 27, 2017

    Thanks. You are a lifesaver.

  48. Ali Baig

     /  July 13, 2017

    Saved my day

  49. Dawn

     /  July 20, 2017

    Great tip I ran into this issue and was able to fix it quickly. Thanks.

  50. Nice fix – helped me at work. Thanks, boss. 🙂

  51. FlailingElbows

     /  July 28, 2017

    Aaaand, another person here who just found the same issue. So, yeah, 7 years and still going strong. Thanks for the post!

  52. Thanks for your post, fixed the issue after many frustrating months.. 🙂

  53. S

     /  August 3, 2017

    Thanks for your post, like you I just clicked thru several times and it opened fine, just figured it was one of those quirky microsoft headaches. Thanks again.

  54. Yeah, here too. Amazing- seven years later and MS still hasn’t fixed a simple bug. Too bad you don’t have a donate button! You could be making some $ off of Microsoft’s continuing ineptitude. 🙂

  55. sukh

     /  August 17, 2017

    Awesome tips. Thanks a lot.

  56. Martin Lagerholm

     /  August 28, 2017

    Great thanks for the help – saved me some time

  57. Thanks – this post definitely saved me some head-scratching!

  58. James

     /  September 26, 2017

    We have discovered if CSV is changed to UTF-8, the SYLK problem disapears (without change ID to Id)

  59. thanks for your post! – and more on this story, if you use your not-SYLK-not-CSV file to create points for your GIS, your site locations will be amusingly scattered across the landscape, to the detriment of your science.

  60. Even other ‘ID’ words trigger the error: IDENTIFIER, IDEALISTIC, IDiocy…

  61. Curt's Mom

     /  December 13, 2017

    Thanks for the info…stupid excel…LOL

  62. ST

     /  August 29, 2018

    Just wanted you to know this old post just probably saved me hours of anger and frustration. THANK YOU!


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