@davidcrown if you go to the github site of InvoicePlane, you will see the tab ‘pull-requests’ at the top of the page.
2 persons made a pull-request for InvoicePlane.
A PR is a Pull-request.
For example: PHP8.1 compatibility by vtq221 · Pull Request #831 · InvoicePlane/InvoicePlane · GitHub
It will ask InvoicePlane to accept the created code. It is an improvement to make InvoicePlane compatible with PHP 8.1
Ahhh thank you. Fingers crossed we see some nice updates. Mine runs pretty solid so as it is but always looking for the shiny next thing
Hi, thanks for your interest in InvoicePlane. A couple of weeks ago we released a beta version (download: InvoicePlane - Downloads - InvoicePlane - An Open Source Invoicing Application) of the brand new v1.6 which brings support for PHP 8 and fixes the issues with the payment providers and other little bugs. Feel free to test it in your local environment and report any bugs to Issues · InvoicePlane/InvoicePlane · GitHub.
The stable release of v1.6 should be out in the next days/weeks.
Glad to see that IP started moving again, thanks everyone!
Someone unfortunately addressed the “there’s not a lot of progress” topic.
In the same topic the “Where’s the support for PHP 8.3” was asked.
Let’s address those questions.
I don’t see real progress here with Invoice Plane. Is the project dead?
Good question!
No, the project is not dead. Contributors are committing to a pull-request almost on a daily basis.
The most active pull-request is the one about e-invoicing l, Zugferd, you name it.
If you want to see how active a project is, the best thing you can do is go to their github repository.
Click on the little clock icon (like a stopwatch).
It will show the commit history of the development branch.
That doesn’t mean inactiveness.
The pull-request is maintained on the submitter’s own repository.
He will finish his work and submits his proposal for source improvements.
The last commit in InvoicePlane’s development branch was 2 days ago
I’m running the current latest version 1.6.2 and was annoyed by it’s sticking to PHP8.1.
So you have a version that was released in January and now mention that you think the project is dead? 
Go ahead and install it on PHP 8.3, no problem at all.
I’ve split off your question to a separate topic.
While you’re on PHP 8.3 you’ll see a lot of errors coming from the vendor directory.
If you wonder which packages are installed there, look in composer.json.
You might find codeigniter in there (version 3), the source of those errors.
Can’t Codeigniter update its version to be compatible with PHP 8.3?
Just like InvoicePlane, contributors have made pull-requests to improve codeigniter for PHP 8.3.
Now we’re waiting on codeigniter’s maintainers to merge those improvements.
The rest i’ll address in the specific topic about PHP 8.3.
Long story short:
CodeIgniter has received a fork. Someone couldn’t wait for CodeIgniter’s contributors, so they made their own improvements and published it.
Is there anyone already working on these topics?
Yes, check the pull-requests
By the way: work on PHP 8.3 is done here: CodeIgniter3 for php-8.2+ and maintained by pocketarc by sudwebdesign · Pull Request #1161 · InvoicePlane/InvoicePlane · GitHub
We made a very conscious decision to stay on PHP 8.1. PHP 8.3 compatibility is offered by one of the contributors in that Pull-request
How active is the current development in general
If you look at the almost daily commits to the e-invoicing branch you can say thag PHP version 1 is developed pretty actively
InvoicePlane is being actively developed in something called a pull-request.
When a pull-request reaches completion it will end up in the development branch.
Some improvements combined will be a new version.
Version 1.6.3 is on its way (once the e-invoicing /zigferd - XRechnung, FacturX branch reaches completion)
In the meantime: for PHP 8.3, check out that pull-request i mentioned