Recent Fix Deployed for Big FanDuel Files with Malformed Lines

Affected users should reupload FanDuel files that hit a specific 500 error line limit.

Today, we identified and deployed a fix affecting a very small number of high volume FanDuel users. If in the past two months you have done a FanDuel upload that had 500 line errors and then aborted, this will have affected you.

Am I affected?

Probably not — we believe only a very small handful of customers are impacted (and we've reached out to you directly to let you know).

If you want to check: Go to your uploads page and if there is a "warning" arrow next to a FanDuel file imported since August 2021, click on it. In the popup, look at the bottom right "errors detected." If this is less than 500, don't worry - you're not affected. If it is exactly 500, then you are affected.

Okay, I've got a FanDuel file with 500 errors. What now?

It's a simple fix: Just download that file (in the popup there's a Download button), then re-upload it to RotoTracker. This will re-import, skipping over lines that already exist and filling in the gaps.

I have loads of files with 500 errors. What should I do?

If you like, you can do a fresh, full sync using RotoTracker Sync. You'll need to make sure you download everything in the last couple of months by overriding default settings and setting a number in the settings that will more than cover your last couple of months history.

Give me the nitty gritty technical details of what actually happened!

Sure thing. So, FanDuel has historically always had a weird bug in its CSV files: For some (but not most!) contests that did not run — those flagged as "ended unmatched" or "voided" — they will not have a date field in the CSV data. We're not talking an empty date (which could make sense if the contest never ran), but literally one less column in the row. That was basically a malformed file. RotoTracker used to try to import that line, wonder why the text "MLB 50/50 Contest $50" is not a valid date, and throw an error.

That's normally fine — RotoTracker will just flag this as an error and move on. That line is not imported (I mean, there's no way to import it without a date), but being that these are voided entries anyway, that's fine.

However, this resulted in lots of users understandably asking why they were getting so many errors in their FanDuel files. So, to make the user experience better, a couple of years ago we put in a special check for this case: So if we see those lines (one less column, no date, on a voided contest), we silently skip the line, rather than flag as an error.

Unfortunately, a couple of months ago FanDuel changed their file format. We updated RT immediately to handle it, but it had an unexpected knock on effect: our special check above stopped working, and these bad lines were reported as errors again, not silent skips.

But even that would be fine because, as noted, errors are just skipped over. Not an issue. However, we recently introduced a change to the importer so that if a line hits 500 errors, there's probably a really serious issue with the file, so let's stop the import. We did this because we had some users upload files of hundreds of thousands of lines long, all with errors (not their fault! that's a DraftKings issue and a story for another time...).

So that resulted in people who had 500 of these bad FanDuel lines having imports stop halfway through and not import the full file. The thing is, that is very rare, because the issue itself is rare. So only really big FanDuel uploads would hit this issue, and only certain players would see it.

So there you go — the full details! Now scroll back to the top and get re-importing!

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