A solution would be to backup and using the DEV version,
github.com/getk2/k2

Just chiming in to say that I have the same error - just updated to Joomla 3.73 yesterday. Articles for my site are only added on the back end, and on occasion the saves throw this:
DateTime::__construct(): Failed to parse time string (-1-11-29 18:00:00) at position 5 (-): Double timezone specification

I'm running K2 v2.7.1 with PHP version 7.0.20

Hopefully the article saves are the only bug.

Hello,

Did you try the DEV version (please backup first).

I don`t understand - what dev version? Where is it?

Try the link in the post :)

I have the same problem. Went to GitHub. No idea how to download or use anything on that page. Will a stable release fixing this bug?

For those unfamiliar with GitHub here a small guide:

1. Backup your site!
2. Create a test environment. The DEV version of K2 means the version can be unstable. Maybe this bug is solved, but some other issues can occur.
3. Go to GitHub ( github.com/getk2/k2 ) and click on the green Clone or download button. In the popup screen choose Download ZIP. You now have an install package (k2-master.zip) which you can install on your test site
4. Test K2 thoroughly. Not just this one feature, but all the essential functions you need on your site. If you come across bugs, check the issue list on GitHub . Report new issues on GitHub (note: you need an account for that)
5. If you are completely sure all is working fine, install the package on your live site. (you did make a backup before installing, didn't you?)
6. Test your live site thoroughly!
7. If this issue is not resolved or some other nasty issue comes up, then report this and hope the K2 developer team fixes this very soon. For the time being use the workaround I posted here.

Thanks for the guide Steven. I've known what GitHub was for years, but never knew quite how to use it, so this is a great hand up.

However, back to topic, this major issue is now 2 months old and still not patched. My client has reported that he tried the date change workaround, but it did not work. I'll try the code edit that Reaction posted and hope this will fix it.

Hi,
We have the same issue but we have it only a week.
Please advise.

regards,
Usu

The same problem.
There is an error if I add tags to the article.

You've found it Микола Корнієнко!
After intensive testing I can confirm that the tagging is the problem. To be specific: when you add a new tag and press enter, the Date Created field is cleared and becomes empty. Thus the date stored is not correct.

I've tested it on K2 v2.8 as well. Here the bug doesn't occur.
The difference is that the (date) publishing and meta fields are not in a sidebar, but in a tab (like the admin interface in v2.7).

Be aware: if you've created your own K2 template (override), you must update this to v2.8, otherwise the new-article form in the frontend becomes a mess and you're not able to write and save new articles.
I want to do some more testing with v2.8 to make sure no other issues are there, before I install it on my live site.

I would like to encourage the developers of K2 to release a stable v2.8 a.s.a.p.

Dev v.2.8.0 did it for me. Thanks.

Steven Trooster wrote: You've found it Микола Корнієнко!
After intensive testing I can confirm that the tagging is the problem. To be specific: when you add a new tag and press enter, the Date Created field is cleared and becomes empty. Thus the date stored is not correct.

I've tested it on K2 v2.8 as well. Here the bug doesn't occur.
The difference is that the (date) publishing and meta fields are not in a sidebar, but in a tab (like the admin interface in v2.7).

Be aware: if you've created your own K2 template (override), you must update this to v2.8, otherwise the new-article form in the frontend becomes a mess and you're not able to write and save new articles.
I want to do some more testing with v2.8 to make sure no other issues are there, before I install it on my live site.

I would like to encourage the developers of K2 to release a stable v2.8 a.s.a.p.

How do I update? I do not understand. Here are my overrides. Thank you

Google Drive

K2 2.8 will be ready within the coming days.
You can use the DEV version located here: github.com/getk2/k2 click on the green button in order to download the extension.

Микола Корнієнко wrote: How do I update? I do not understand. Here are my overrides. Thank you

Read my post about updating here:
www.joomlaworks.net/forum/k2-en/47780-error-double-timezone-specification?start=10#162860

Yes, this does need to be addressed. It has been happening to me, but by reading this forum I have learned to make a change to the "Creation date" found under Publishing & Metadata, although it seems to revert back at some point. So it is something the team will need to look at.

Thanks!

Is there a fix for the version 2.7.1 to apply? The fix from Reaction didn't worked for me and I'am currently not able to do a full update of K2.

Krikor wrote: K2 2.8 will be ready within the coming days.

Again we are not seeing any progress in the development of K2. Everyone who cares about updating to the newest Joomla version should experience the same problem. I don't want to update to any GitHub-Dev-Version of K2. What is the exact fix for this problem?

Just wondering if there is an estimated release date for a stable v2.8 of K2 as it has now been two weeks since the last message saying it will be ready in the coming days. Our client is experiencing this issue but would prefer to use the final stable release rather than using a possibly unstable dev version.

Thanks

Within the coming days, a last issue is being tackled (modals) and 2.8 will be ready or the DEV will be 100% safe.