diff --git a/Cargo.lock b/Cargo.lock
index 3db5c45d..ee31955a 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -876,7 +876,7 @@ checksum = "37909eebbb50d72f9059c3b6d82c0463f2ff062c9e95845c43a6c9c0355411be"
 
 [[package]]
 name = "fbuild-bench-fastled-examples"
-version = "2.3.1"
+version = "2.3.3"
 dependencies = [
  "fbuild-library-select",
  "fbuild-packages",
@@ -887,7 +887,7 @@ dependencies = [
 
 [[package]]
 name = "fbuild-build"
-version = "2.3.1"
+version = "2.3.3"
 dependencies = [
  "async-trait",
  "blake3",
@@ -919,7 +919,7 @@ dependencies = [
 
 [[package]]
 name = "fbuild-cli"
-version = "2.3.1"
+version = "2.3.3"
 dependencies = [
  "blake3",
  "clap",
@@ -949,7 +949,7 @@ dependencies = [
 
 [[package]]
 name = "fbuild-config"
-version = "2.3.1"
+version = "2.3.3"
 dependencies = [
  "fbuild-core",
  "include_dir",
@@ -963,7 +963,7 @@ dependencies = [
 
 [[package]]
 name = "fbuild-core"
-version = "2.3.1"
+version = "2.3.3"
 dependencies = [
  "libc",
  "prost",
@@ -982,7 +982,7 @@ dependencies = [
 
 [[package]]
 name = "fbuild-daemon"
-version = "2.3.1"
+version = "2.3.3"
 dependencies = [
  "async-trait",
  "axum",
@@ -1022,7 +1022,7 @@ dependencies = [
 
 [[package]]
 name = "fbuild-deploy"
-version = "2.3.1"
+version = "2.3.3"
 dependencies = [
  "async-trait",
  "espflash",
@@ -1045,7 +1045,7 @@ dependencies = [
 
 [[package]]
 name = "fbuild-header-scan"
-version = "2.3.1"
+version = "2.3.3"
 dependencies = [
  "criterion",
  "rayon",
@@ -1055,7 +1055,7 @@ dependencies = [
 
 [[package]]
 name = "fbuild-library-select"
-version = "2.3.1"
+version = "2.3.3"
 dependencies = [
  "bincode",
  "blake3",
@@ -1074,7 +1074,7 @@ dependencies = [
 
 [[package]]
 name = "fbuild-packages"
-version = "2.3.1"
+version = "2.3.3"
 dependencies = [
  "axum",
  "bzip2",
@@ -1101,14 +1101,14 @@ dependencies = [
 
 [[package]]
 name = "fbuild-paths"
-version = "2.3.1"
+version = "2.3.3"
 dependencies = [
  "fbuild-core",
 ]
 
 [[package]]
 name = "fbuild-python"
-version = "2.3.1"
+version = "2.3.3"
 dependencies = [
  "base64",
  "fbuild-core",
@@ -1130,7 +1130,7 @@ dependencies = [
 
 [[package]]
 name = "fbuild-serial"
-version = "2.3.1"
+version = "2.3.3"
 dependencies = [
  "async-trait",
  "base64",
@@ -1152,7 +1152,7 @@ dependencies = [
 
 [[package]]
 name = "fbuild-test-support"
-version = "2.3.1"
+version = "2.3.3"
 dependencies = [
  "fbuild-config",
  "fbuild-header-scan",
diff --git a/Cargo.toml b/Cargo.toml
index a14935ae..22133d51 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -26,7 +26,7 @@ exclude = ["dylints/ban_raw_subprocess"]
 libraries = [{ path = "dylints/*" }]
 
 [workspace.package]
-version = "2.3.2"
+version = "2.3.3"
 edition = "2021"
 rust-version = "1.94.1"
 license = "MIT OR Apache-2.0"
diff --git a/crates/fbuild-build/src/compiler.rs b/crates/fbuild-build/src/compiler.rs
index 403ec971..972af755 100644
--- a/crates/fbuild-build/src/compiler.rs
+++ b/crates/fbuild-build/src/compiler.rs
@@ -652,7 +652,20 @@ pub fn compile_source(
         tracing::info!("compile: {}", args.join(" "));
     }
 
-    let result = run_command(&args_ref, compile_cwd.as_deref(), None, None)?;
+    let mut result = run_command(&args_ref, compile_cwd.as_deref(), None, None)?;
+
+    if !result.success() {
+        if let Some(zccache) = compiler_cache {
+            if crate::zccache::output_has_stale_daemon_error(&result.stdout, &result.stderr) {
+                tracing::warn!(
+                    "zccache protocol mismatch detected; stopping daemon and retrying compile"
+                );
+                crate::zccache::stop(zccache)?;
+                crate::zccache::ensure_running(zccache)?;
+                result = run_command(&args_ref, compile_cwd.as_deref(), None, None)?;
+            }
+        }
+    }
 
     if result.success() {
         std::fs::write(command_hash_path(output), rebuild_signature)?;
diff --git a/crates/fbuild-build/src/managed_zccache.rs b/crates/fbuild-build/src/managed_zccache.rs
index 01a81a49..2df5338c 100644
--- a/crates/fbuild-build/src/managed_zccache.rs
+++ b/crates/fbuild-build/src/managed_zccache.rs
@@ -24,12 +24,12 @@ use fbuild_core::{FbuildError, Result};
 
 /// The zccache release fbuild pins. Bump in lockstep with the floor that
 /// the rest of the toolchain expects.
-pub const MANAGED_ZCCACHE_VERSION: &str = "1.12.9";
+pub const MANAGED_ZCCACHE_VERSION: &str = "1.12.10";
 
 /// GitHub release tag for [`MANAGED_ZCCACHE_VERSION`]. The zccache release
 /// workflow tags without a `v` prefix, while the per-asset filenames carry
 /// `v<version>` — keep both spellings in sync when bumping.
-const RELEASE_TAG: &str = "1.12.9";
+const RELEASE_TAG: &str = "1.12.10";
 
 /// Source repository for managed downloads.
 const REPO: &str = "zackees/zccache";
diff --git a/crates/fbuild-build/src/zccache.rs b/crates/fbuild-build/src/zccache.rs
index d5321961..22cc947d 100644
--- a/crates/fbuild-build/src/zccache.rs
+++ b/crates/fbuild-build/src/zccache.rs
@@ -213,6 +213,47 @@ pub fn ensure_running(zccache: &Path) -> Result<()> {
     if output.status.success() {
         tracing::info!("zccache daemon running");
         Ok(())
+    } else if output_has_stale_daemon_error(
+        &String::from_utf8_lossy(&output.stdout),
+        &String::from_utf8_lossy(&output.stderr),
+    ) {
+        tracing::warn!("zccache daemon appears stale; stopping and retrying start");
+        let _ = stop(zccache);
+        std::thread::sleep(std::time::Duration::from_millis(250));
+
+        let mut retry_cmd = std::process::Command::new(zccache);
+        retry_cmd
+            .arg("start")
+            .stdout(Stdio::piped())
+            .stderr(Stdio::piped());
+
+        #[cfg(windows)]
+        {
+            use std::os::windows::process::CommandExt;
+            const CREATE_NO_WINDOW: u32 = 0x08000000;
+            retry_cmd.creation_flags(CREATE_NO_WINDOW);
+        }
+
+        let retry = retry_cmd.output().map_err(|e| {
+            FbuildError::BuildFailed(format!(
+                "failed to spawn zccache daemon via `{}` start: {}",
+                zccache.display(),
+                e
+            ))
+        })?;
+        if retry.status.success() {
+            tracing::info!("zccache daemon running after stale-daemon recovery");
+            Ok(())
+        } else {
+            let message = format_zccache_start_failure(
+                zccache,
+                retry.status.to_string(),
+                &retry.stdout,
+                &retry.stderr,
+            );
+            tracing::warn!("{message}");
+            Err(FbuildError::BuildFailed(message))
+        }
     } else {
         let message = format_zccache_start_failure(
             zccache,
@@ -225,6 +266,55 @@ pub fn ensure_running(zccache: &Path) -> Result<()> {
     }
 }
 
+/// Stop the zccache daemon for this user, if one is running.
+pub fn stop(zccache: &Path) -> Result<()> {
+    let mut cmd = std::process::Command::new(zccache);
+    cmd.arg("stop")
+        .stdout(Stdio::piped())
+        .stderr(Stdio::piped());
+
+    #[cfg(windows)]
+    {
+        use std::os::windows::process::CommandExt;
+        const CREATE_NO_WINDOW: u32 = 0x08000000;
+        cmd.creation_flags(CREATE_NO_WINDOW);
+    }
+
+    let output = cmd.output().map_err(|e| {
+        FbuildError::BuildFailed(format!(
+            "failed to spawn zccache daemon via `{}` stop: {}",
+            zccache.display(),
+            e
+        ))
+    })?;
+
+    if output.status.success() {
+        Ok(())
+    } else {
+        Err(FbuildError::BuildFailed(format_zccache_start_failure(
+            zccache,
+            output.status,
+            &output.stdout,
+            &output.stderr,
+        )))
+    }
+}
+
+/// zccache can leave a previous-version daemon running across fbuild upgrades.
+/// The new client then fails wrapped compiles with a protocol mismatch until
+/// the old daemon is stopped.
+pub fn output_has_protocol_mismatch(stdout: &str, stderr: &str) -> bool {
+    stdout.contains("protocol version mismatch") || stderr.contains("protocol version mismatch")
+}
+
+pub fn output_has_stale_daemon_error(stdout: &str, stderr: &str) -> bool {
+    output_has_protocol_mismatch(stdout, stderr)
+        || stdout.contains("lost connection to daemon")
+        || stderr.contains("lost connection to daemon")
+        || stdout.contains("not accepting connections")
+        || stderr.contains("not accepting connections")
+}
+
 fn format_zccache_start_failure(
     zccache: &Path,
     status: impl std::fmt::Display,
@@ -597,6 +687,23 @@ mod tests {
         assert!(message.contains("fbuild daemon logs"));
     }
 
+    #[test]
+    fn detects_zccache_protocol_mismatch_from_stderr_or_stdout() {
+        let mismatch =
+            "zccache[err][R]: broken connection to daemon: protocol error: protocol version mismatch: expected v16, received v15";
+
+        assert!(output_has_protocol_mismatch("", mismatch));
+        assert!(output_has_protocol_mismatch(mismatch, ""));
+        assert!(output_has_stale_daemon_error(
+            "",
+            "zccache[err][R]: lost connection to daemon (no response)"
+        ));
+        assert!(!output_has_protocol_mismatch(
+            "ordinary stdout",
+            "ordinary stderr"
+        ));
+    }
+
     #[test]
     fn path_arg_for_compile_cwd_returns_workspace_relative_path() {
         let tmp = tempfile::TempDir::new().unwrap();
diff --git a/pyproject.toml b/pyproject.toml
index 9b5508bf..dde0d9e7 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,6 +1,6 @@
 [project]
 name = "fbuild"
-version = "2.3.2"
+version = "2.3.3"
 description = "PlatformIO-compatible embedded build tool (Rust implementation)"
 readme = "README.md"
 requires-python = ">=3.10"