Warning: Footprint of component 'Q1' changed ...?


Running the 8 May Kicad build. After reading in the new netlist in pcbnew, I get a Warning. I would like to know how to to fix this. ERC and DRC output is clean.

I’ve tried deleting the transistor in the schematic and inserting it afresh. Even after saving and re-saving the pcb over the course of weeks the warning has not gone away. As far as I can see it is set up exactly like Q2 which does not generate a warning. While this is not a fatal error, I would prefer to have no warnings at all.

Here are a couple pictures. I’m ready to send whatever is requested to resolve this.


The warning tells you that the footprint you got in the layout differs from the footprint Q1 should have according to the netlist.

To solve thoroughly:

  • go to EEschema, open CvPCB
  • check settings for Q1 and Q2
  • set up Q1 as you have Q2 (I assume that is what you want as Q1 has a problem)
  • create a new netlist, save the schematic
  • go to PCBnew
  • DELETE the Q1 footprint
  • load the new netlist
  • position the Q1 footprint (which should now appear) where it was before

PS: I assume somewhen in the past you changed the footprint association for Q1 in EEschema/CvPCB, but had the old footprint already in the layout and didn’t set up the netlist (re)load dialog correctly to CHANGE the footprints.

PPS: you could also try to select ‘Change Footprint’ before loading the netlist, but I don’t know how ‘screwed up’ your files are (or what else starts to come loose) in case I missed something there (as I don’t see everything involved). If you try this - make a copy of the WHOLE project folder beforehand.


Oh, thank you so much for the fix! Yes, it is now fixed…

Things were OK on the Eeschema side. I had to select Change before I loaded the netlist on the Pcb side…

While I think my project is under control now, I must confess that I did spend the first four weeks of my learning effort flailing about and chasing my tail :smile:


I like that philosophy! I also work until the DRC is clean; you won’t catch me saying, “It’s just a warning.”.

@Joan_Sparky laid out steps to clear this squawk. Keep in mind that the DRC is saying, “You have specified two different footprints for Q1 at different places in your project. That looks suspicious, and may indicate that a human made a mistake during the board design. I don’t know which footprint you really mean to use, so please reconcile this disagreement.”.

The first question to decide is, which of these two footprints do you actually want to use: the one from the stock KiCAD library called “TO_SOT_Packages_THT.pretty”, or the footprint from your personal library, “JOESKICAD”? Once that has been decided you can make the necessary changes in the appropriate files so that all references to Q1’s footprint (in the schematic, the netlist, and the board layout) are in agreement.



The “Import Netlist” tool has a “Dry Run” option that I find very helpful. I use it before I import a netlist, with only the “Errors” and “Warnings” reported. (OK, sometimes I watch for “Actions” too, depending on what I changed in the netlist since the last import.) This gives me advance warning that maybe I have screwed up someplace, and I can correct it before anything actually changes on the board.

I also save everything (schematic, board, library archive, project file, etc) to back-up copies before I import a netlist, since the netlist import can NOT be undone. Of course, if you notice something going awry during the netlist import you can simply exit and close PCBNew WITHOUT SAVING the board file. The next time you start PCBNew the board will be the same as it was just before the attempted import.



When it comes to software and computer programs I don’t think there has EVER been a case of “Love at first sight”.



Dry Run: I just gave it a try. So, you can get error messages without messing up the board. Nice.


Yeah, even though I go into these things with the Zen notion of acceptance leading to transcendence, invariably I go in chomping, barking and swearing. After I burn myself out a voice says, “Dude, why don’t you do a little more reading and calm down.” I’m happy to say I am at that stage now. :expressionless:


The 20th century physicist Dr. Jacob Bronowski said,

In other words, you gotta do some of that flailing and barking before the reading has much effect. Or at least carefully watch somebody else do the flailing and barking.


p.s. - You HAVE read Bronowski’s “The Ascent of Man”, haven’t you? Or at least watched the television series? (Nearly half a century after its production, it’s still cited as exceptional documentary television. I think the whole series is now available on the web.) Every engineer and scientist needs to be exposed to “Ascent of Man”.


Oh yes, I watched that show and was inspired by Bronowski. I raved about him so much that my girl friend gave me his book for Christmas which I voraciously read. Loved it. Ah, that book is long gone, but one thing I’ve always remembered: his proof of the Pythagorean Theorem without any math! He said, “the Pythagorean Theorem is the single most important theorem in mathematics.”