A file that I've been working on all of the sudden fails to grab brush strokes, fills, or changes of any sort. My only option is to start copying layer by layer, merging what is possible, and start with a new file. Even then I lose data "outside of the canvas", making some of the work dirty.

Anyway, good luck, I don't think this will ever be solved by intention. This wasn't the first time. <-- Sorry about this attitude!

How do you think anyone could solve this? You're simply not giving any information anyone could do anything with.

Start with telling us which OS you're using, which version of Krita, what colorspace and channel depth, what image dimensions -- consider sharing the "unresponsive" file, even. Tell us whether this is an animation or not.

Linux / Debian 9
4000x4000, RGBA 8 bit (sRGB-elle-V2-srgbtrc.icc) image
Krita 4.2.0 pre-alpha (git 1af5c34 ) is the latest one I have but not the only version where this occurs.
https://ufile.io/4gs7c <-- this is my personal artwork in it's original form, but for the greater good....

Somehow, you've managed to 'select none' so your attempts at painting will not have any effect. If you do Select -> Select All from the main menu bar then that will get things back to normal. You can then do Select -> Deselect to get rid of the dotted box around the picture if you want to. (This is something that always confuses me compared to GIMP which is what I'm most used to .)

Somebody else may know how you got into this situation but I can't figure it out. You have an impressive painting there with some nice textures and highlights.

Thank you very much indeed! Selecting All and Deselecting is the workaround.

ahabgreybeard wrote:Somehow, you've managed to 'select none' so your attempts at painting will not have any effect.

The how in somehow might have been first selecting an area then substracting everything from that selection.

That will work if you draw a selection rectangle (in Subtract mode) with boundaries that surround the canvas and are off canvas. However, the selection indicator icon (lower left of screen) will give you the appropriate numbers for the rectangle you drew and you will be able to draw outside the selection rectangle (off canvas). If you Select All then Invert Selection you get a similar situation.

Your .kra file showed a selection indicator with x=0, y=0, width=0, height=0. You really had selected 'nothing'. I can't reproduce this situation.