diff --git a/src/engine.ts b/src/engine.ts
index a034e554..7db8b255 100644
--- a/src/engine.ts
+++ b/src/engine.ts
@@ -33,6 +33,13 @@ const re = {
 	// The numbers of #791 that count what came before: $i, $c, $m and $M with their cousins, like $i00 or $M_
 	runNumbers: /\$[icmM](?![A-Za-z])/,
 	matchNumbers: /\$[mM](?![A-Za-z])/,
+	// A path that is not clear as it is printed: a space at the start or the end, or a char that can not be seen,
+	// like a line break from echo or a zero-width space
+	unclearPath: /^\s|\s$|[\x00-\x1f\x7f-\x9f\u200b-\u200f\u2028-\u202e\u2060-\u2064\ufeff]/,
+	// The chars of unclearPath that JSON.stringify does not escape
+	invisibleChars: /[\x7f-\x9f\u200b-\u200f\u2028-\u202e\u2060-\u2064\ufeff]/g,
+	// The end of the message of a failed file call, like `, open 'nope.txt'`
+	fileCallInMessage: /, \w+( '.*')?$/s,
 };
 
 // Only the version ends up in the bundle
@@ -696,13 +703,27 @@ function getFinalReplacement(replacement, conf: any) {
 		try {
 			return readReplacementFile(replacement, conf);
 		} catch (e) {
-			return panic('The replacement file can not be read:', replacement);
+			return panic('The replacement file can not be read:', pathAndReason(replacement, e));
 		}
 	}
 
 	return replacement;
 }
 
+// The path and why it can not be read, like `nope.txt (ENOENT: no such file or directory)`.
+// A path that is not clear as it is printed is shown as JSON, with each char that can not be seen escaped.
+function pathAndReason(filepath, e) {
+	let shownPath = filepath;
+	if (re.unclearPath.test(filepath)) {
+		shownPath = JSON.stringify(filepath).replace(
+			re.invisibleChars,
+			char => '\\u' + char.charCodeAt(0).toString(16).padStart(4, '0')
+		);
+	}
+	// The call and the path at the end of the message are told already
+	return shownPath + ' (' + e.message.replace(re.fileCallInMessage, '') + ')';
+}
+
 // Each replacement file is read once, also when the code of --js gives the same path for many matches
 function readReplacementFile(filepath, conf) {
 	conf.replacementFiles ??= new Map();
@@ -720,16 +741,16 @@ function codeReplacement(file, config, text, numbers) {
 	if (!config.replacementFile) {
 		return code;
 	}
-	// A path that can not be read is an error once, and its matches are left as they are
-	const failed = new Set();
+	// A path that can not be read is an error once in the run, and its matches are left as they are
+	config.unreadableFiles ??= new Set();
 	return (...args) => {
 		const filepath = String(code(...args));
-		if (!failed.has(filepath)) {
+		if (!config.unreadableFiles.has(filepath)) {
 			try {
 				return readReplacementFile(filepath, config);
 			} catch (e) {
-				failed.add(filepath);
-				error('The replacement file can not be read:', filepath);
+				config.unreadableFiles.add(filepath);
+				error('The replacement file can not be read:', pathAndReason(filepath, e));
 			}
 		}
 		return args[0];
diff --git a/test/engine/replacement-file.test.js b/test/engine/replacement-file.test.js
index 121bccd2..19abca35 100644
--- a/test/engine/replacement-file.test.js
+++ b/test/engine/replacement-file.test.js
@@ -59,7 +59,9 @@ describe('--replacement-file', () => {
 	test('that can not be read stops the run before any file is changed', async () => {
 		fs.writeFileSync('my.file', 'foo');
 		const result = await rr('foo', 'nope.txt', {includeGlob: ['my.file'], replacementFile: true});
-		expect(result.err).toStartWith(' ❌ The replacement file can not be read: nope.txt');
+		expect(result.err).toStartWith(
+			' ❌ The replacement file can not be read: nope.txt (ENOENT: no such file or directory)'
+		);
 		expect(result.exit).toBe(3);
 		expect(fs.readFileSync('my.file', 'utf8')).toBe('foo');
 	});
@@ -68,7 +70,7 @@ describe('--replacement-file', () => {
 		const config = {pipedData: 'foo', replacementJs: true, replacementFile: true};
 		expect(await rr('o', '"nope.txt"', config)).toEqual({
 			out: 'foo',
-			err: ' ❌ The replacement file can not be read: nope.txt\n\n',
+			err: ' ❌ The replacement file can not be read: nope.txt (ENOENT: no such file or directory)\n\n',
 			exit: 2,
 		});
 	});
diff --git a/test/fix/818.test.js b/test/fix/818.test.js
new file mode 100644
index 00000000..c4029dc5
--- /dev/null
+++ b/test/fix/818.test.js
@@ -0,0 +1,43 @@
+// https://github.com/mathiasrw/rexreplace/issues/818
+// A replacement file that could not be read gave no reason, and with --js the error came once for each file.
+import {describe, test, expect} from 'bun:test';
+import fs from 'fs';
+import {rr, rrStatus} from '../helper.js';
+
+describe('#818 a replacement file that can not be read', () => {
+	test.each([
+		['is not there', 'nope.txt', 'nope.txt (ENOENT: no such file or directory)'],
+		['is a folder', 'adir', 'adir (EISDIR: illegal operation on a directory)'],
+		[
+			'has a zero-width space',
+			'no\u200bpe.txt',
+			'"no\\u200bpe.txt" (ENOENT: no such file or directory)',
+		],
+		['has a C1 char', 'no\u0085pe.txt', '"no\\u0085pe.txt" (ENOENT: no such file or directory)'],
+		[
+			'has a line break at the end, like from echo',
+			'a.txt\n',
+			'"a.txt\\n" (ENOENT: no such file or directory)',
+		],
+		[
+			'has a backslash, like a Windows path',
+			'my\\dir/nope.txt',
+			'my\\dir/nope.txt (ENOENT: no such file or directory)',
+		],
+	])('tells the reason when the path %s', async (name, filepath, text) => {
+		fs.mkdirSync('adir');
+		fs.writeFileSync('a.txt', 'X');
+		const result = await rr('X', filepath, {includeGlob: ['a.txt'], replacementFile: true});
+		expect(result.err).toStartWith(' ❌ The replacement file can not be read: ' + text);
+	});
+
+	test('with --js is told once in the run, not once for each file', async () => {
+		fs.writeFileSync('a.txt', 'X');
+		fs.writeFileSync('b.txt', 'X');
+		const config = {includeGlob: ['*.txt'], replacementJs: true, replacementFile: true};
+		const status = await rrStatus('X', '"nope.txt"', config);
+		expect(status.errors).toEqual([
+			'The replacement file can not be read: nope.txt (ENOENT: no such file or directory)',
+		]);
+	});
+});