diff --git a/bootstrap/preflight.php b/bootstrap/preflight.php
index 8ef7d226..9c2b6a54 100644
--- a/bootstrap/preflight.php
+++ b/bootstrap/preflight.php
@@ -62,9 +62,23 @@ function projectsend_preflight_failure(string $root): ?array
     $envFile = $root.'/.env';
     $hasEnvFile = is_file($envFile);
 
+    // A .env that is there but unreadable looks exactly like one that was
+    // never created — is_file() is false either way, since it has to follow
+    // the link and stat the target — and the two need opposite advice.
+    // Reported from the official Docker image, where .env is a symlink into
+    // storage/: the image left /var/www/html world-writable and owned by a
+    // uid that no longer existed, so the kernel's fs.protected_symlinks
+    // refused to let the php-fpm worker follow it. Every request said "no
+    // .env file was found" while `docker exec ... cat .env`, as root, printed
+    // it back perfectly — which is the most misleading pair of facts this
+    // guard could possibly hand somebody.
+    $unreadableEnv = $hasEnvFile ? ! is_readable($envFile) : is_link($envFile);
+
     // Fall back to a cheap read of just APP_KEY from the file — we are not
-    // going to boot Dotenv or parse the whole thing for one value.
-    if ($appKey === null && $hasEnvFile) {
+    // going to boot Dotenv or parse the whole thing for one value. Skipped
+    // when the file cannot be read, or file() emits a PHP warning into the
+    // page this guard exists to keep clean.
+    if ($appKey === null && $hasEnvFile && ! $unreadableEnv) {
         foreach (file($envFile, FILE_IGNORE_NEW_LINES | FILE_SKIP_EMPTY_LINES) ?: [] as $line) {
             if (preg_match('/^\s*(?:export\s+)?APP_KEY\s*=\s*(.*)$/', $line, $m) === 1) {
                 // Strip the surrounding quotes Dotenv would also strip.
@@ -79,6 +93,18 @@ function projectsend_preflight_failure(string $root): ?array
         return null;
     }
 
+    if ($unreadableEnv) {
+        return [
+            'ProjectSend cannot read its configuration',
+            'A <code>.env</code> is in place, but the user PHP runs as cannot read it — or, if it '
+                .'is a symlink, cannot follow it. Note that <code>root</code> is exempt from both '
+                .'checks, so reading the file over <code>docker exec</code> or <code>sudo</code> '
+                .'proves nothing here.',
+            "Compare who owns the file with who PHP runs as, and check the directory holding it:\n\n"
+                ."ls -ln .env\nstat -c '%n %U %a' . .env",
+        ];
+    }
+
     if (! $hasEnvFile) {
         return [
             'ProjectSend is not configured yet',
diff --git a/docker/production/Dockerfile b/docker/production/Dockerfile
index 9b3b5d07..f7b04d91 100644
--- a/docker/production/Dockerfile
+++ b/docker/production/Dockerfile
@@ -80,10 +80,24 @@ WORKDIR /var/www/html
 COPY --chown=www-data:www-data app/ /var/www/html/
 
 # storage/ and bootstrap/cache must be writable by the runtime user.
+#
+# /var/www/html itself needs re-owning as well, and it is easy to miss: COPY
+# --chown re-owns what it copies *into* the directory, never the directory,
+# so it keeps what the base image gave it — uid 82 (the www-data this image
+# replaced above) and mode 1777, which php:*-fpm sets so that an image can
+# run as an arbitrary user. Left that way, the directory is world-writable,
+# sticky, and owned by nobody the container knows about, and the kernel's
+# fs.protected_symlinks (on by default on Ubuntu, Debian and most current
+# distributions) then refuses to let the php-fpm worker follow the .env
+# symlink the entrypoint puts there. Root is exempt, so `docker exec ... cat
+# .env` reads it back perfectly while every real request 503s with
+# "ProjectSend is not configured yet".
 RUN mkdir -p storage/app/files storage/framework/cache storage/framework/sessions \
              storage/framework/views storage/logs bootstrap/cache \
     && chown -R www-data:www-data storage bootstrap/cache \
     && chmod -R u+rwX storage bootstrap/cache \
+    && chown www-data:www-data /var/www/html \
+    && chmod 755 /var/www/html \
     && mkdir -p /run/nginx
 
 # The whole of storage/, not just storage/app/files. Uploaded files are the
diff --git a/docker/production/entrypoint.sh b/docker/production/entrypoint.sh
index 49e1b3c4..27efce96 100755
--- a/docker/production/entrypoint.sh
+++ b/docker/production/entrypoint.sh
@@ -40,7 +40,15 @@ if [ ! -f storage/.env ]; then
     cp .env.example storage/.env
     chown www-data:www-data storage/.env
 fi
+#
+# The symlink is owned by the runtime user, not by root who creates it:
+# fs.protected_symlinks lets a process follow a symlink in a world-writable
+# sticky directory only when it owns the link (or the directory). The image
+# no longer leaves /var/www/html in that state, so this is the second lock
+# on the same door — cheap, and it is what keeps the failure from coming
+# back silently if that directory's mode ever drifts.
 [ -L .env ] || ln -sf storage/.env .env
+chown -h www-data:www-data .env
 
 if [ -z "$APP_KEY" ] && ! grep -q '^APP_KEY=base64:' storage/.env; then
     echo "projectsend: generating APP_KEY (first boot, persisted to the storage volume)"
diff --git a/tests/Unit/PreflightTest.php b/tests/Unit/PreflightTest.php
index d2111528..77a416fa 100644
--- a/tests/Unit/PreflightTest.php
+++ b/tests/Unit/PreflightTest.php
@@ -68,6 +68,34 @@ it('fails when a .env exists with no APP_KEY line at all', function (): void {
     expect(projectsend_preflight_failure(preflightFixture(null, true)))->not->toBeNull();
 });
 
+it('says so when .env is a symlink it cannot follow, rather than that none exists', function (): void {
+    // The official image symlinks .env into storage/. When that link cannot
+    // be followed — a missing target, or a directory whose permissions stop
+    // the web server user traversing it — every stat says "no such file",
+    // and "copy .env.example" is then exactly the wrong thing to be told.
+    $dir = preflightFixture(null, false);
+    symlink($dir.'/storage/.env', $dir.'/.env');
+
+    $failure = projectsend_preflight_failure($dir);
+
+    expect($failure)->not->toBeNull()
+        ->and($failure[0])->toBe('ProjectSend cannot read its configuration')
+        ->and($failure[1])->toContain('cannot read it')
+        ->and(projectsend_preflight_command($failure[2]))->toContain('ls -ln .env')
+        ->and(projectsend_preflight_command($failure[2]))->not->toContain('cp .env.example');
+});
+
+it('says so when .env exists but its permissions deny the reader', function (): void {
+    $dir = preflightFixture('base64:'.base64_encode(random_bytes(32)), true);
+    chmod($dir.'/.env', 0000);
+    clearstatcache();
+
+    $failure = projectsend_preflight_failure($dir);
+
+    expect($failure)->not->toBeNull()
+        ->and($failure[0])->toBe('ProjectSend cannot read its configuration');
+})->skip(fn (): bool => function_exists('posix_geteuid') && posix_geteuid() === 0, 'root can read anything, so the mode says nothing');
+
 it('reads a quoted APP_KEY the way Dotenv would', function (): void {
     $dir = preflightFixture('"base64:'.base64_encode(random_bytes(32)).'"', true);