Blocking waiting for file lock on package cache / build directory Rust Origin: Application & API OSI layer 7 · Application Last updated 5 Nov 2026

Cargo: Blocking waiting for file lock on package cache / on build directory

Another cargo process (or rust-analyzer/IDE) holds the lock, so this command waits.

Exact message you may see Blocking waiting for file lock on package cacheBlocking waiting for file lock on build directoryBlocking waiting for file lock on artifact directoryBlocking waiting for file lock on shared package cachecargo blocking waiting for file lock
Seen on: Rust Linux

Meaning

Wait for the other process, or stop it (pkill cargo). Common with rust-analyzer running cargo check in the same target dir — set a separate rust-analyzer.cargo.targetDir or CARGO_TARGET_DIR. A stale lock on network filesystems can also hang. It's not an error unless it never finishes.

Common causes

  • IDE/rust-analyzer running checks
  • Parallel terminals running cargo
  • Hung cargo process
  • Shared network filesystem for CARGO_HOME or target
  • CI jobs sharing a cache dir

⚡ Quick fix

  1. Wait or pkill -f cargo if stuck
  2. Separate target dir for rust-analyzer (rust-analyzer.cargo.targetDir: true)
  3. Avoid sharing ~/.cargo across concurrent jobs without care

Detailed fix by platform

Linux

  1. ps aux | grep -E "cargo|rustc|rust-analyzer" | head

How to diagnose

  1. Process — Who holds it?
  2. IDE — rust-analyzer?
  3. FS — Network?

🔧 Still not fixed?

Many errors look alike. If the steps above didn’t solve it, one of these is probably what you’re facing:

Where this error sits

Origin: Application & API. Errors that are often confused with or caused by this one (click to open):

Cannot start a runtime from within a runtime (Tokio) — Rust: thread 'main' panicked: Cannot start a runtime from within a runtime — a function like `block_on` tried to block a thread that drives async tasks (Rust)Cannot start a runtim…cargo: failed to get from registry (spurious network error) — Cargo: warning: spurious network error (2 tries remaining): [35] SSL connect error / error: failed to download from `https://index.crates.io/...` (Rust)cargo: failed to get …cargo: failed to select a version for the requirement — Cargo: error: failed to select a version for the requirement `serde = "^2.0"` — candidate versions found which didn't match: 1.0.197 (Rust)cargo: failed to sele…E0004: non-exhaustive patterns — Rust: error[E0004]: non-exhaustive patterns: `None` not covered (Rust)E0004: non-exhaustive…E0015: cannot call non-const function in constants — Rust: error[E0015]: cannot call non-const function `String::from` in constants (Rust)E0015: cannot call no…E0038: the trait cannot be made into an object — Rust: error[E0038]: the trait `Shape` cannot be made into an object (not dyn compatible) (Rust)E0038: the trait cann…E0061: this function takes N arguments but M were supplied — Rust: error[E0061]: this function takes 2 arguments but 1 argument was supplied (Rust)E0061: this function …E0063: missing field in initializer of struct — Rust: error[E0063]: missing field `age` in initializer of `User` (Rust)E0063: missing field …Blocking …

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