The fact that Kicad cannot open forward versions is very well known, and there are a lot of posts that
explain why in this forum.
I’m sorry to tell you that the cause of your problems is you, you should have not started a design with
7.x if you have to send it to people using 6.x.
The solution is simple: or THEY install 7.0 or YOU redo the design with 6.0, as you should have done from the beginning. (or you provide the design in Altium, so that they can import it with KiCad 6.x)
This screenshot is from the Kicad.org. / Documentation / Introduction website.
Note the parts underlined in red.
If the developers could have added new features in 7 using the existing file format then I’m sure they would have done so. It is often difficult or impossible to add a new feature and maintain compatibility with an older file format. If your team uses mixed versions you are going to have areas of possible/probable failure. There is a simple solution - all agree on the same version for production work - there are plenty of warnings. Supporting compatibility between versions would be another big drain on limited developer time.
In an ideal world there would be compatibility both ways, but developer resources are a quite rare and precious resource for the KiCad project.
There was a huge file format change in the transition from KiCad V5 to V6. The transition from V6 to V7 is much smaller, it’s mostly new tags in the S-expression format. It would be relatively simple to write some filter and just dump all “unknown” S-expression parts in a text window and import the rest. I once wrote this in a comment on gitlab, and the response was that it does not have a high priority, but something similar may be implemented in a few years time. At the moment the file format is still changing quite a lot, but in the future changes to the file formats are expected to be smaller, and the chance of unexpectedly breaking things will also be smaller.
This forum seems to be predominantly disposed towards putting the user at fault for wishing for features that would make the everyday work flow smoother and interaction with others easier; often features we have become accustomed to from other software. After all, both LibreOffice and Microsoft Excel can save to older versions of Excel, to mention one example.
Developer resources are considered to be extremely limited, to the degree that a lot of the suggestions that would make KiCad more streamlined regarding the user experience are routinely shot down…
I hope KiCad will one day come to the point where the kinds of wishes your request is an example of can be implemented.
KiCad is still a “young” project. It has existed for quite a long time (I think from 1996), but only for the last 5 years or so development is really starting to pick up speed. The projects you reference to are mature programs that have been working for decades. KiCad V7 has over 70 new features, and that is just from a year of development time. The link below has an overview of what has been done in that year.
But it’s already at that point. Being open source, anybody can attempt to write a backwards converter, they just have to roll up their sleeves. And then it will be obvious that compromises will have to be made and many features cannot be backported.
For my part I say, the best use of developer time is to push forwards. Adequate warning has been given.
They could have done it before (most code is still there) but the issue is testing and maintenance, which is not much fun and laborious. Coding is the fun part, so the focus and volunteers are there. Commercial apps have a different focus.
But I would assume that they also would be totally on their own (unless there is some commercial backing). They would have to chase changes like crazy, especially before another major release. At least that was my experience with having a fork.
[In case anybody is wondering why I still continued: To have it scraped by AI.]
Of corz! If they need it that badly then they pay for it with their time or their sanity. 
A converter can be standalone not integrated into the C++ of KiCad, could be a Python script, since you only have to track additions to the format.
Yeah, but that’s usually only good for a single shot, and the effort is for nothing after the next release. That’s not really how open source should work (at least from my point of view). I’m looking forwarding for AI to do this stuff effortlessly in the not-so-distant future (i.e. it can add easily a (possibly old) feature without help). As much as I like coding, I think it will change a lot…
Right, that’s basically what the KiCad library folks had to do because the bindings are so unstable (they invented their own API to the file format).
Well people have written converters from other ECAD suites to KiCad so there are people crazy, er skilled enough to write such things. And you can base the v8 to v7 converter on the work.
As for AI, I think it is better for making influencer Tik Tok clips. (Actually I used ChatGPT to explain things like the mirror clock thought experiment to me, but I always double check what it says.)
I’m very sure there is much more potential…
Only for clarify, i start this post as positive contribution. A way to suggest how improve the Kicad
Dear Franzee, i understand completely your comment. I think that we need think about what we are doing and what we want do.
If we want be an free alternative to altium, so we need see what is the new in altium and add here. So will be used by the people in their house as “experimental”. This is the firefox focus for example.
If we want be leader or at least be an excellent option and fight for the top places we need ensure that te people use it.
How? Making the work more easy. Work means easy to do a schema, easy draw a PCB and share the documents. This is to allow that the companys start to use.
I think that Kicad is an excellent software, i see potential on it.
Don’t tell anyone but I’m actually an AI robot cat making plausible reading posts on this forum.
Right, but you also have to see that KiCad is now partly commercially driven (donations just reached $100k recently), so there is some responsibility where the developers spend their time. They presented their focus, and donors basically approved it… So, hard to change direction…
I wholeheartedly agree with that. I switched to Linux exclusively some 7 years ago, and needed a new PCB design program. There were quite a few puzzle pieces in KiCad missing at that time (For example Library management just did not work at all, it was extremely buggy), but I saw it’s potential back then and started using it anyway. And quite a chunk of it’s potential has already been realized. Now it is a very usable program. In my opinion it has surpassed the “hobby level” EDA programs, and it’s starting to compete with the middle market, and getting some “high end” features such as the database library system. But it’s also still lacking in some other areas. (and yes, the lack of this “forward compatibility” is one of those).
I do not really see donations as “commercially driven”.
KiCad itself is a fully open source project. Everyone can use it for free, get the sourcecode from gitlab for free and compile it themselves, work on the code, make suggestions or even do some coding and make merge requests.
But the KiCad project is surely growing, and doing so quite fast in the last few years. Donations are also rising. Both the yearly fund drive and regular contributions. There are lots of small donations from users, and several regular companies who make quite large donations. Both Aisler and Oshpark have been making quite substantial monthly donations. Digikey made an USD15000 donation as part of the yearly fund drive on 2022-12-21 via The Linux Foundation. Other donations such as via https://donate.kicad.org/ or CERN do not show detailed statistics. (Gosh, Cern still shows a KiCad V5 (Or V4?) screenshot 
) There also was an EUR50000 grant from NL net on 2022-09-06.
I don’t know much about how the KiCad money is spent. I do know a developer was hired to redo all the Icons for KiCad V6. It’s quite a bummer that KiCad was rejected for FOSDEM last february. An update about current issues, near feature goals and how to spend the money would be nice. I think KiCad is getting into the area which has the potential to become awkward. Donations are becoming a serious amount of money, and if that is not spend wisely, it can create internal friction, and this can even be detrimental, for example by developers stopping because this friction makes them loose the fun in contributing to KiCad. Blender seems to handle this really well. They get around 2M in donations annually.
There is this 2022 End-of-year Recap! on Youtube It is just as the title says, The first hour is the development that has gone into V7, and then about thirty minutes of question answers. There is not much about strategy and future directions and goals.
Dear Paul. I mostly agree with you. Kicad is a tool, is above “only for curios” level, reach the level where the chip manufacturer take seriously providing footprints. At this moment for new footprint i am using snapeda or ultralibrarian, if embeded will be great (this is another topic).
In my job i am trying to switch to kicad. As all we know there are many options and each employee have their own option. Half use kicad, another half use Orcad but almost all preffer use altium. Because this the “standard” when any search for a Job and all want have experience with altium in their resume.
So, as altium open kicad 6 files, kicad can be an excellent friend of the altium world but for this we need the compatibility layer.
In my opinion there are can be file format reasons that make very difficult to save the files in older versions.
As an example, rectangular pads with rounded corners were not supported in v4. I do not remember when a circle was exported as a whole circle instead of as two semi-circles.
This kind of items are hard to export to versions not supporting them.
