diff --git a/CHANGELOG.md b/CHANGELOG.md
index 83640d4c..b47642cf 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -21,6 +21,10 @@
   - Before: every time the launcher started, it put Link Play back on Same network, so players who only play over the internet had to pick Internet again each time
   - Now: Internet through the public relay or a friend's relay stays chosen. A direct address, a relay on this PC (off until you turn it on again) and old room codes are still cleared at start
   - Thanks to Sakamoto on Discord for the report
+- **Set up says why it failed when the game folder has an accent in its path** (#630)
+  - Before: with the game in a folder such as `OneDrive\Área de Trabalho`, a failed Set up showed only "The game build failed (exit code: 1)" and setup.log had no reason, because the reason named that folder in a form the launcher could not read
+  - Now: the game build writes its messages as UTF-8 and the launcher reads every line of a tool's output, so the real error reaches the screen and setup.log
+  - Still not: this shows the error, it does not fix it. A game folder inside OneDrive can still fail while OneDrive syncs the build files; a folder outside OneDrive (such as `C:\Games`) avoids that
 
 ### Gameplay
 - **Camera aim keeps the block you aimed at while a move plays** (#535)
diff --git a/game-build/release_b/pkp_build.py b/game-build/release_b/pkp_build.py
index c63a447b..eabe3031 100644
--- a/game-build/release_b/pkp_build.py
+++ b/game-build/release_b/pkp_build.py
@@ -79,6 +79,12 @@
 import time
 from concurrent.futures import ThreadPoolExecutor, FIRST_COMPLETED, wait
 
+# The launcher reads this script's stdout and stderr as UTF-8, and lift() reads its --lift-one children's the same way. Under -I
+# Python writes a pipe in the ANSI code page (cp1252 on a Portuguese Windows), so an @error naming a folder such as
+# "OneDrive\Área de Trabalho" reached the launcher as bytes it could not read, and Set up failed with no reason (#630).
+for _stream in (sys.stdout, sys.stderr):
+    if hasattr(_stream, 'reconfigure'):
+        _stream.reconfigure(encoding='utf-8', errors='replace')
 HERE = os.path.dirname(os.path.abspath(__file__))
 RECOMP = os.path.join(HERE, 'recomp')
 SDK = os.path.join(HERE, 'sdk')
diff --git a/launcher/src-tauri/examples/first_run.rs b/launcher/src-tauri/examples/first_run.rs
index 3bcf3310..6430be3c 100644
--- a/launcher/src-tauri/examples/first_run.rs
+++ b/launcher/src-tauri/examples/first_run.rs
@@ -5,6 +5,8 @@
 //! it fetches the Linux build tools first (host.rs). Prints each phase's time.
 
 // host.rs reaches the launcher's own modules, so an example carries the same set the binary declares (main.rs), by path.
+#[path = "../src/child_lines.rs"]
+mod child_lines;
 #[allow(dead_code, clippy::all)]
 #[path = "../src/config.rs"]
 mod config;
diff --git a/launcher/src-tauri/examples/shader_setup.rs b/launcher/src-tauri/examples/shader_setup.rs
index 44a9b479..9968923f 100644
--- a/launcher/src-tauri/examples/shader_setup.rs
+++ b/launcher/src-tauri/examples/shader_setup.rs
@@ -6,6 +6,8 @@
 //!   cargo run --example shader_setup -- --native <harness dll> <corpus> <out> [--gentle]
 
 // host.rs reaches the launcher's own modules, so an example carries the same set the binary declares (main.rs), by path.
+#[path = "../src/child_lines.rs"]
+mod child_lines;
 #[allow(dead_code, clippy::all)]
 #[path = "../src/config.rs"]
 mod config;
diff --git a/launcher/src-tauri/src/child_lines.rs b/launcher/src-tauri/src/child_lines.rs
new file mode 100644
index 00000000..6e734b93
--- /dev/null
+++ b/launcher/src-tauri/src/child_lines.rs
@@ -0,0 +1,40 @@
+//! A child process's output (the game build, the shader tools, the DLSS download) read line by line.
+//!
+//! `BufRead::lines()` ends at the first line that is not UTF-8, and `map_while(Result::ok)` then drops the rest of the stream.
+//! A Windows tool writes in the ANSI code page, so a line naming a folder such as "OneDrive\Área de Trabalho" ended the
+//! reader: the game build's `@error` line never arrived and Set up failed with no reason in setup.log (#630). Here such a line
+//! is read lossily and the stream goes on.
+
+use std::io::{BufRead, BufReader, Read};
+
+/// The lines `r` gives until it ends or fails, without their line ending ("\n" or "\r\n"). Bytes that are not UTF-8 read as
+/// U+FFFD.
+pub fn lines<R: Read>(r: R) -> impl Iterator<Item = String> {
+    let mut r = BufReader::new(r);
+    std::iter::from_fn(move || {
+        let mut buf = Vec::new();
+        match r.read_until(b'\n', &mut buf) {
+            Ok(0) | Err(_) => None,
+            Ok(_) => {
+                if buf.last() == Some(&b'\n') {
+                    buf.pop();
+                    if buf.last() == Some(&b'\r') {
+                        buf.pop();
+                    }
+                }
+                Some(String::from_utf8_lossy(&buf).into_owned())
+            }
+        }
+    })
+}
+
+#[cfg(test)]
+mod tests {
+    #[test]
+    fn a_line_that_is_not_utf8_does_not_end_the_stream() {
+        // "@error C:\...\Área\r\n" as cp1252 writes it (0xC1), then a line after it
+        let out: &[u8] = b"@progress lift 0 4 x\r\n@error C:\\\xC1rea\r\nlast";
+        let got: Vec<String> = super::lines(out).collect();
+        assert_eq!(got, ["@progress lift 0 4 x", "@error C:\\\u{FFFD}rea", "last"]);
+    }
+}
diff --git a/launcher/src-tauri/src/dlss.rs b/launcher/src-tauri/src/dlss.rs
index e99a385f..7b70b57a 100644
--- a/launcher/src-tauri/src/dlss.rs
+++ b/launcher/src-tauri/src/dlss.rs
@@ -4,7 +4,6 @@
 //! downloads the file from NVIDIA's own GitHub repository at a fixed tag and checks its sha256, into `<game>/upscalers/streamline`.
 
 use serde::Serialize;
-use std::io::{BufRead, BufReader};
 use std::path::{Path, PathBuf};
 use std::process::Stdio;
 
@@ -76,9 +75,9 @@ pub fn fetch(game_dir: &Path, tools_dir: &Path, mut report: impl FnMut(Progress)
     }
     let mut child = cmd.stdout(Stdio::piped()).stderr(Stdio::piped()).spawn().map_err(|e| format!("could not start the download ({}): {}", py.display(), e))?;
     let err = child.stderr.take().unwrap();
-    let err_tail = std::thread::spawn(move || BufReader::new(err).lines().map_while(Result::ok).last().unwrap_or_default());
+    let err_tail = std::thread::spawn(move || crate::child_lines::lines(err).last().unwrap_or_default());
     let mut error: Option<String> = None;
-    for l in BufReader::new(child.stdout.take().unwrap()).lines().map_while(Result::ok) {
+    for l in crate::child_lines::lines(child.stdout.take().unwrap()) {
         if let Some(rest) = l.strip_prefix("@progress ") {
             let mut it = rest.splitn(4, ' ');
             let _phase = it.next();
diff --git a/launcher/src-tauri/src/gamebuild.rs b/launcher/src-tauri/src/gamebuild.rs
index b0a7360b..f04df188 100644
--- a/launcher/src-tauri/src/gamebuild.rs
+++ b/launcher/src-tauri/src/gamebuild.rs
@@ -18,7 +18,6 @@
 //! Its crate-local imports are host.rs (with download.rs) and runtime_api.rs, so `examples/first_run.rs` can build the files alone.
 
 use std::fs;
-use std::io::{BufRead, BufReader};
 use std::path::{Path, PathBuf};
 use std::process::{Command, Stdio};
 use std::sync::atomic::{AtomicBool, Ordering};
@@ -293,11 +292,11 @@ pub fn run(job: &Job, tools: &Tools, cancel: &AtomicBool, mut report: impl FnMut
     let out = child.stdout.take().unwrap();
     let err = child.stderr.take().unwrap();
     let (tx, rx) = std::sync::mpsc::channel::<String>();
-    std::thread::spawn(move || BufReader::new(out).lines().map_while(Result::ok).for_each(|l| drop(tx.send(l))));
+    std::thread::spawn(move || crate::child_lines::lines(out).for_each(|l| drop(tx.send(l))));
     let elog = job.log.clone();
     let err_tail = std::thread::spawn(move || {
         let mut tail: Vec<String> = Vec::new();
-        for l in BufReader::new(err).lines().map_while(Result::ok) {
+        for l in crate::child_lines::lines(err) {
             if let Some(f) = &elog {
                 f(&format!("stderr: {}", l));
             }
diff --git a/launcher/src-tauri/src/harness.rs b/launcher/src-tauri/src/harness.rs
index 4e1d1333..0733bb09 100644
--- a/launcher/src-tauri/src/harness.rs
+++ b/launcher/src-tauri/src/harness.rs
@@ -1,7 +1,7 @@
 //! Running the shader translator (tools/shaders/harness, `spirv_harness.exe`) for `shaders`: a run, a worker that runs chunk after
 //! chunk in one process, and why a failed run failed.
 use std::fs;
-use std::io::{BufRead, BufReader, Write};
+use std::io::Write;
 use std::path::{Path, PathBuf};
 use std::process::{Child, ChildStdin, Command, Stdio};
 use std::sync::atomic::{AtomicBool, Ordering};
@@ -164,12 +164,12 @@ impl Worker {
             .map_err(|e| format!("could not start {}: {}", name, e))?;
         let out = child.stdout.take().unwrap();
         let (tx, lines) = mpsc::channel::<String>();
-        std::thread::spawn(move || BufReader::new(out).lines().map_while(Result::ok).for_each(|l| drop(tx.send(l))));
+        std::thread::spawn(move || crate::child_lines::lines(out).for_each(|l| drop(tx.send(l))));
         let err = child.stderr.take().unwrap();
         let (etx, stderr) = mpsc::channel::<String>();
         std::thread::spawn(move || {
             let mut tail: Vec<String> = Vec::new();
-            for l in BufReader::new(err).lines().map_while(Result::ok) {
+            for l in crate::child_lines::lines(err) {
                 tail.push(l);
                 if tail.len() > 12 {
                     tail.remove(0);
diff --git a/launcher/src-tauri/src/main.rs b/launcher/src-tauri/src/main.rs
index 3805b522..48f7f3e5 100644
--- a/launcher/src-tauri/src/main.rs
+++ b/launcher/src-tauri/src/main.rs
@@ -4,6 +4,7 @@
 mod backup_cmds;
 mod branding;
 mod branding_cmds;
+mod child_lines;
 mod cli;
 mod config;
 mod dialogs;
diff --git a/launcher/src-tauri/src/shaders.rs b/launcher/src-tauri/src/shaders.rs
index 4096c3af..f021b84b 100644
--- a/launcher/src-tauri/src/shaders.rs
+++ b/launcher/src-tauri/src/shaders.rs
@@ -22,7 +22,7 @@
 use serde::{Deserialize, Serialize};
 use std::collections::HashSet;
 use std::fs;
-use std::io::{BufRead, BufReader, Write};
+use std::io::Write;
 use std::path::{Path, PathBuf};
 use std::process::{Child, Command, Stdio};
 use std::sync::atomic::{AtomicBool, AtomicU64, AtomicUsize, Ordering};
@@ -455,13 +455,13 @@ pub(crate) fn run_tool(mut cmd: Command, cancel: &AtomicBool, idle: bool, log: O
     let (tx, rx) = mpsc::channel::<String>();
     let out = child.stdout.take().unwrap();
     let tx2 = tx.clone();
-    std::thread::spawn(move || BufReader::new(out).lines().map_while(Result::ok).for_each(|l| drop(tx2.send(l))));
+    std::thread::spawn(move || crate::child_lines::lines(out).for_each(|l| drop(tx2.send(l))));
     let err = child.stderr.take().unwrap();
     let (etx, erx) = mpsc::channel::<String>();
     let elog = log.cloned();
     std::thread::spawn(move || {
         let mut tail: Vec<String> = Vec::new();
-        for l in BufReader::new(err).lines().map_while(Result::ok) {
+        for l in crate::child_lines::lines(err) {
             if let Some(f) = &elog {
                 f(&format!("stderr: {}", l));
             }