What does "error RC2175: icon.ico is not in 3.00 format" mean

Question

I recently ported a project from VC6 to VS2012, fairly successfully. Trying to change out the splash screens and icon that were previously bad looking bitmaps. From the looks of it, 256 color bitmaps.

So, I made new bitmaps and tried to put them in and constantly get: error RC2175: icon.ico is not in 3.00 format

I've searched for what this means and got: http://msdn.microsoft.com/en-us/library/s49y5a1h(v=VS.80).aspx error RC2175 : resource file res\icon3.bmp is not in 3.00 format? And the worthless MSDN page.

I tried making these bitmaps as 24-bit, 256 color and 16 color. I also tried all the different modes Gimp allows mimicing the other, original icons. Also tried loading the bitmaps in MS Paint and re-saving without success.

And this point, I would just like some indication on what 3.00 format is and how to get around it.

Answer 1

So, I made new bitmaps

Which is surely where this went wrong. An .ico file is not just a bitmap. It is a file format of its own that's capable of storing multiple bitmaps. Which have bitmasks that indicate what part of the image is transparent or inverted.

So the best way to read the error message is for what it says: "this is not an icon". It can't meaningfully say more than that, it isn't going to try to guess what kind of file it actually might be. That you could load the file in MS Paint is another strong indication that the file was actually a bitmap and not an icon, Paint can't load icons. It doesn't have the plumbing to allow you to select the specific image from the .ico file you want to edit, nor any way to edit the bitmasks. Renaming a image file to .ico does not create a valid icon file.

You can create or edit icons with Visual Studio or one of many popular icon editing utilities.

Answer 2

And the answer is here. Funny how different searches on different days yield different results:

icon is not in 3.00 format