Summary: Chrome version 83.0.4103.61 broke concrete5 editing (and affected other CMSs), but there are two ways to fix this problem:

• the next Chrome update, version 83.0.4103.97, fixed the problem. If you have any problems editing or using concrete5 with the Chrome browser, please try updating to the latest version.
• an upgrade to concrete5, version 8.5.3, also fixed the problem. This update includes security fixes and other improvements, so you should update to the latests version when possible.

Note: this post has been updated

In the latest Chrome Version 83.0.4103.61, jquery-form misbehaves, causing an error when you save blocks. Our Open Source friends at Drupal are experiencing similar issues. We're already working on a fix marked to release concrete5 version 8.5.3 in June. 

Here is a screenshot of the error,  after clicking save in your block using Chrome Version 83.0.4103.61

What now?

The quickest fix is to use Firefox, Safari, for a short time and wait for concrete5 version 8.5.3 update for release in June. We're working diligently on a fix because keeping developers out of their favorite dev tools is a big deal to us. Korvin is working with jquery-form and our community is helping out in every way. 

Can not use a different browser, and wait for concrete5 version 8.5.3 in June? At PortlandLabs we are manually fixing this issue using BikerDave's Pull Request. Find your favorite developer, and apply the fix manually. 

We've set up a forum post where we can discuss, assist, and ask questions here. No need to be a developer to participate in discussions; this bug hinders developers and editors alike. 

I want to give a special thank you a few community members:
First thank you, Tom Rogers, for notifying us on twitter. Holiday weekends are when I spend time updating a few personal sites I run. You saved me many hours of troubleshooting, swearing, and headaches. 

BikerDave, thank you for the speedy Pull Request, this is what makes open source great. A shout out for Hissy, one of our loyal partners in Japan, for jumping in to assist.

Want to get involved? 

We're always looking for tutorials, videos, and Pull Requests. Join our Slack Channel for more information. 

Thanks!

Jess & Korvin

Update

Both Chrome 83.0.4103.97 (currently the latest release as of 2020 June 04) and Chrome 84 will fix this issue withuot any code changes. As of June 1st (2020/06/01), Chrome 84 is still in beta status but can be downloaded from the Chrome beta page. The brief screencast below shows Chrome 84 in action