Site Update (December 2025)

[euler]

Sorry if the extended downtime today interfered with your plans to solve problems. As some of you know, 2038 marks the end of the Unix timestamp. So with 2038 fast approaching (; a large back end update was carried out today to shift all of the internal time/date DB values from Unix timestamps to DateTime objects. This has taken a number of weeks to modify all of the scripts on my local machine to handle the new DateTime objects throughout the site. It has also required significant changes to the DB tables.

I have done as much testing as possible to ensure that everything is working but until the site undergoes extensive use, it is unlikely that I will have covered all possible interactions. If you notice any issues, I would be very grateful if you took the time to report the issue here.

I wish the changes today brought something more exciting, but it was a necessary change. So I'd like to thank you for your patience and be assured I've already begun thinking about how to handle the end of DateTime objects at the end of year 9999.

[Icy]

It seems problems that I've solved "many moons ago" do not register as solved and show me an input box.

Example:


Edit: Uploaded image to imgBB instead of imgur.

[philiplu]

The Progress/Awards and Progress/Posts pages are completely blank for everything below the top-level navigation bar.

[euler]

@icy001: Thank you for reporting. Just so you know, no one in the UK or most of Europe can see images from imgur. The governments have introduced such restrictive legislation relating to online content that many companies outside of Europe have taken the simpler option of just blocking content to those countries.

However, I was able to understand the issue and I think it should be fixed. It actually impacted 13 scripts in total!

@philiplu: I'll look into that now.
[edit]Progress page error should be fixed. Thanks for letting me know. I don't know how I missed that one! [/edit]

[gauna]

In Progress/Awards, 'The Centanarian' is showing my total solve count, not the amount of different days.

[euler]

Well spotted! It should now be reporting the correct number of unique days.

[Icy]

Sort by Best Posts appears to be broken, showing only "- Best Posts" in the header and a blank white screen below.

[euler]

Thank you for taking the time to report this issues. That should be fixed now too.

[philiplu]

Something noticed by people on the Discord - on the Archives page, Sort by "Solved By" doesn't work any longer. Pressing the up/down arrows in that column sorts up/down by ID instead.

[euler]

That was a subtle one. Good find. You might need to refresh the page, but it should work now.

[bloebje]

If I view the history of a friend, the problems that I solved 'before time began' appear in red instead of green.

[euler]

I think I've fixed that one. Could you check that it is working now?

[i707107]

The History page doesn't show anything.

[euler]

That was weird! It should be showing again now.

[bloebje]

I think I've fixed that one. Could you check that it is working now?

Yes it works fine now, thank you

[tytoalba]

Hi,

I solved a few problems 2 and 3 days ago, after resetting my progress - as I always do when I start with another language. Today they all disappeared, my progress is reset. I may enter the solutions again, but now the system is apparently detecting fast solves as cheating, so I don't think it's a good idea either. What am I supposed to do?

[euler]

I'm not quite sure what you mean about detecting as cheating? If you reset your progress, this will completely clear all problems you have solved. As far as the system is concerned you are a new member. An established status requires members to meet minimum thresholds with their solve record. Once achieved you will be able to switch to public status.

[tytoalba]

Let me rephrase.

1. All my progress was reset without any action on my part, **after** I did a few programs (31 precisely). This happened between 12/31/2025 and today, and I suspect it's a bug. I **didn't** reset my progress since I played recently (I was just rewriting some solutions in R). By the way, it wasn't established enough since the profile couldn't go public.

2. If I just enter the solutions quickly, it **will** be detected as cheating. Or at least it's what the site says. I can simulate playing faithfully, but I don't see the point: I don't cheat and I have the solutions to ~150 problems in various programming languages (mainly Python and Java), accumulated over the years, since at least 2011.

So, okay it's my fault for having reset at some time (as I said, I do this when I switch languages) - on the other hand I didn't predict the system would start to control players. However I didn't reset this time, the system did. I was merely replying to "If you notice any issues, I would be very grateful if you took the time to report the issue here."

[euler]

I can't rule anything out, but the solve data is atomised. Each solve is stored in the DB as a separate row, so it's not like during an update your entire solve record could become corrupted/deleted. The script capable of performing a mass delete of your solve data is the part of your account page where you choose to reset your progress. You couldn't even accidentally resubmit a previous page as the request is tokenised and the token is destroyed upon use.

I can see that you had solved 31 problems in the DB backup on 31 December and it was not in the DB backup from 1 January. I am more than happy to restore those if you would like me to do that. But I'm still confused as to what message you're seeing that suggests you're cheating? If you're referring to not being able to switch to public because your account hasn't reached an established status, this is nothing unusual. It is is due to thresholds which we do not share publicly and your account at that stage will not have met those requirements. You will just need to keep on solving at a sensible rate.

[tytoalba]

Yes, it's perfect if you can restore the solved problems. Thank you!

As to cheating: I only say that if I enter solutions quickly to recover the account as it was, it will probably me detected as cheating. I don't claim it did. It's just what the site says at https://projecteuler.net/about=private_locked: "When people simply enter one answer after another in succession to several problems, they are not using Project Euler in the way it was intended and they show little respect for the time and care taken to curate each problem. Consequently, whilst this behaviour pattern continues, they are effectively making a choice to exclude themselves from the Project Euler community."