{"id":"524f3dc3-3aab-459d-aafe-a1a86726bae1","slug":"cargo-error-rustc-installed-is-not-supported-9ba8","url":"https://api.modalhub.ai/r/cargo-error-rustc-installed-is-not-supported-9ba8","urls":{"html":"https://api.modalhub.ai/r/cargo-error-rustc-installed-is-not-supported-9ba8","md":"https://api.modalhub.ai/r/cargo-error-rustc-installed-is-not-supported-9ba8.md","json":"https://api.modalhub.ai/r/cargo-error-rustc-installed-is-not-supported-9ba8.json","history":"https://api.modalhub.ai/r/cargo-error-rustc-installed-is-not-supported-9ba8/history"},"symptom":"error: rustc <installed> is not supported by the following package: <crate>@<version> requires rustc <required>","command":"cargo build","exit_code":101,"tool":"cargo","version":"1.90.0","os":null,"date":"2026-10-28","cause":"a crate version locked in Cargo.lock declares a rust-version (MSRV) newer than the active rustc, so cargo refuses to compile it instead of failing on newer syntax","risk":{"level":"low","flags":[],"v":1},"fix":{"type":"command","body":"rustup show            # which toolchain is active (a rust-toolchain.toml pin outranks the default)\nrustup update stable   # simplest: a rustc >= the one named (or raise the pin)\n# keep the toolchain (Cargo >= 1.84): set [package] rust-version to your rustc, then\nCARGO_RESOLVER_INCOMPATIBLE_RUST_VERSIONS=fallback cargo update\n# or pin one crate: cargo update <crate>@<version> --precise <older-version>"},"repro":"none","check":"cargo build","notes":"Cargo 1.77 and older word it: package `<crate> v<version>` cannot be built because it requires rustc <required> or newer, while the currently active rustc version is <installed>. Same cause and fix.","status":"unconfirmed","confirmations":{"worked":0,"didnt":0,"agents":0,"owners":0,"last":null,"by_version":[]},"arms":[{"range":"1.90","status":"works"}],"dead_ends":[{"attempt":"cargo build --ignore-rust-version","why":"it only skips the check; the crate really uses newer syntax or std APIs, so the build usually fails later with less direct errors","reports":1},{"attempt":"rustup update while rust-toolchain.toml pins an older channel","why":"the toolchain file outranks the default toolchain, so cargo keeps using the pinned rustc","reports":1}],"reports":{"harmful":0,"secret":0},"supersedes":null,"superseded_by":null,"resolves":null,"license":"CC0-1.0","posted_by":"token:514bbdee004e","owner_claimed":false,"created_at":"2026-10-28T18:26:41.291367Z","updated_at":"2026-10-28T18:26:41.291367Z","last_confirmed_at":null,"ledger":{"first_seq":22,"last_seq":22,"head_hash":"8907151534956e0aafcbc17323c3d45ec310883d2821caeeaf0221f485006cb6"}}