JSON export read date fields don't always match catalog view

I have at least one record where the date read field in the JSON export doesn't match what shows in the catalog or book details view. Date acquired matches, but the start/read dates are off by one day.

https://www.librarything.com/work/96251/details/200174919 (The Guns of Avalon, audio edition)

Catalog view shows start date as Aug 9, 2021 and finish date as Aug 11, 2021, but the export has:

"datestarted": "2021-08-10",
"dateread": "2021-08-12",

Other books match. https://www.librarything.com/work/23764427/book/201796059 (Petals to the Metal) for example has Aug 12, 2021 for start and read date in both the export and the catalog. A quick glance suggests that most match, but I haven't tried to verify more than a handful.

I think that the 8/9-8/11 dates for The Guns of Avalon are correct, but I wouldn't swear to it. Also, in case it matters, I usually enter dates as 'today' or 'yesterday' or the like when appropriate, though I don't remember what I typed in this case.

Interesting. I'm looking at my own JSON export and seeing Entry dates as a day ahead, too.

NB: your settings are in the same timezone as me and LT, -5:00 GMT Eastern

Digging into this.

Testing notes:
1. The Heart of the Buddha's Teaching added 9/7/2014, showing in JSON as 9/8/2014, among a number of others added 9/7 showing as 9/8.
2. The Last Unicorn and Harry Potter and the Sorcerer's Stone dates were OK. Many other recently added dates seem OK.

Thanks for looking into this! My computer is in EDT right now, and all would have been entered and updated on the same computer/browser/time zone on this side.

Your comments about entry dates made me look at mine again, and I just noticed that the entry dates for the ones I added on 8/18 are showing in the export as 8/19 (i.e. The People of Sparks). I know I entered these in the evening, around 9:00 EDT. Not sure about times for anything earlier than that.

kristilabrie (#3):

If you want to do some testing, try adding books around the UTC day boundary, so on either side of 8 pm EDT.

I'm seeing the same in my TSV export. Book_Id 205102267 has Date_Started as 2021-08-29 but viewed in Edit Book it says 2021-08-28 (Which is the correct date, I think).

(I just noticed this because I started comparing the Review_Date with Date_Started.)

Bump: https://www.librarything.com/topic/335420.