What are the breaking changes in version 9.*?

[Rubenisme]

I see that version 9 is out, but I cannot find where the breaking changes are listed, I do see the Releases page with changes but I don't really see breaking changes at first glance.
Anyone know how "safe it is" to upgrade from 8 to 9?

I see this was asked for the previous version here, but didn't see one for version 9 (9.02 now).

[baynezy]

I upgraded and had to rollback as there is a bug #2044 where if you have a trailing character after your parameter, it gets dropped.

[Rubenisme]

Thanks, there is a new major version (10) out and it's not clear what the breaking changes are in both of them. :(

[timosnel]

We use Refit in our own libraries and we get compilation errors when trying to upgrade from version 8 to 9 or 10.

The current release notes provide no guidance at all unfortunately.

[glennawatson]

There is no separate hand-written "breaking changes" page for 9.x or 10.x; the only curated breaking-changes notes in the README are for 6.x and 11.x. So here is the practical summary for 8 -> 9 -> 10.

The big breaking change in 9.x is target frameworks. Refit 8 multi-targeted net462; netstandard2.0; net6.0; net8.0. Refit 9 dropped net6.0 and targets net462; netstandard2.0; net8.0; net9.0 (10 adds net10.0). If you (or one of your dependencies) target net6.0/net7.0, that is the most common cause of upgrade failures - move to net8.0+ or stay on netstandard2.0.

Other things that bite people moving across 9/10:

• The source generator was reworked across these versions (explicit interface emission, diagnostics, path-substitution handling). If you had code relying on generator internals or got new RefitN diagnostics, that is expected; fix per the diagnostic message.
• 10.x changed the default System.Text.Json setup (custom enum converter, inferred-types converter). Most apps are unaffected, but custom JsonSerializerOptions assumptions can surface.
• 11.x is where the documented exception-model breaking change lives (ApiRequestException, IApiResponse.Error becomes ApiExceptionBase). See "Breaking changes in 11.x" in the README.

If you want the exact API-level deltas, the most reliable source is the public API snapshot diff between tags, e.g. compare src/Refit.Tests/API/ApiApprovalTests.Refit.*.verified.txt across the 8.0.0, 9.0.2, 10.x and 11.x tags - every public surface change shows up there.

For "how safe is 8 -> 9": if your TFM is net8.0+ or netstandard2.0 it is usually a clean bump; the compile errors others reported were generally net6.0 targeting or downstream libraries still on the old generator. Note there was a separate query-trailing-character bug reported as #2044 in 9.x; check whether it affects your routes before upgrading.