You may have started getting deprecation warnings because some methods in the `Error` trait have been deprecated [1] in favor of a different mechanism.

Then, you may have configured warnings to result in compilation errors in your build/project, however, I would argue this situation is not what most people would understand as "code not compiling due to a compiler update".

[1]: https://doc.rust-lang.org/std/error/trait.Error.html

In my case it failed to build, maybe it was a different problem, maybe the compiler had at some point emitted errors instead of warnings.

I don't remember and it doesn't really matter other than we had build issues and it was unexpected.

Deprecation should be the only change to Error in the last six years. It hasn’t moved. If you ever get a repro would love to hear about it! This kind of thing doesn’t happen at the scale we’re at anymore, if it did there would be an uproar.