I have a simple project that relies on pyo3. Currently/previously, it was using version 0.20.0, but recently a new version has landed which is version 0.21.2. I am looking for a Cargo command that will update the dependency, even if that then means I have to go back through the source and fix any breaking changes that were introduced. However, if I run:

> cargo update pyo3 --precise 0.21.2

Or just equally:

cargo update pyo3

Then I am met with the following error:

error: failed to select a version for the requirement `pyo3 = "^0.20.0"`
candidate versions found which didn't match: 0.21.2
location searched: crates.io index
required by package `eight-ball v0.1.0 (/home/harry/Documents/eight-ball)`
perhaps a crate was updated and forgotten to be re-vendored?

Here is the Cargo.toml file as it was before the update:

[package]
name = "eight-ball"
version = "0.1.0"
edition = "2021"

# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
[lib]
name = "eight_ball"
crate-type = ["cdylib"]

[dependencies]
itertools = "0.12.1"
pyo3 = "0.20.0"

If I go to the Cargo.toml file and manually change the version on pyo3 to the latest version and then build, everything works fine. It doesn’t seem like what I am looking for is something crazy, so I feel like I am just using Cargo wrong.

What I wanted was to just be able to run a Cargo command to update me to version 0.21.2, but the obvious choice didn’t work, and I couldn’t see a –force option or similar. I don’t know why it thought that I was so set on remaining at version 0.20.0.

How can I use cargo to update the dependencies on my project without having to modify the Cargo.toml directly?