# Common mistakes and verified fixes > Each row was compiled with PHPue 0.0.3's `convert_pvue_file()`. Many of these do not throw an error: the page silently renders the wrong thing. When something looks wrong, read the compiled PHP (`?compile=views/page.pvue` in dev, or `convert_pvue_file()` from the CLI). ## Template output | You write | What happens | Fix | |---|---|---| | `{{ $user.name }}` | PHP concatenation: wrong output and warnings | `{{ $user['name'] }}` or `{{ $user->name }}` | | `{{ $tags }}` (array) | `htmlspecialchars()` TypeError | `{{ implode(', ', $tags) }}` | | `{{ !$x }}`, `{{ (int)$x }}`, `{{ 'text' }}` | printed literally | `{{ $x ? '' : 'no' }}`, `{{ intval($x) }}`, `` | | `{{ total() }}` meant for Alpine | compiled as a PHP call: `Call to undefined function total()` | `x-text="total()"` | | `class="x" {{ $on ? 'aria-current="page"' : '' }}` | quotes escaped: `aria-current="page"` | `aria-current="{{ $on ? 'page' : 'false' }}"` or `` | | `p-else`, `p-show`, `p-model` | not directives; left as dead attributes | negated `p-if`, raw PHP, `value="{{ $x }}"` | | `p-if` element without its closing tag | only the opening tag is wrapped; content always renders | close the element | | `p-for="item of $items"` | not converted (`data-phpue-invalid-p-for`) | `p-for="$item in $items"` | | Literal `{{ $x }}` in documentation text | gets compiled | `{{ $x }}` | ## Blocks and files | You write | What happens | Fix | |---|---|---| | A closing script tag inside a PHP string or comment in `` in the App header | `$` interpolated by the heredoc | move JS to a file or `` | | `phpue_set_lang('cy')` in a view | too late, `` already printed | App script or `backend/` | | `__DIR__ . '/data/x.json'` in a view | breaks after `php index.php build` | `getcwd() . '/data/x.json'` | | Variables named `$routing`, `$current_route`, `$b404`, `$input`, `$action` | reset by the compiled preamble | other names | ## AJAX | You write | What happens | Fix | |---|---|---| | `return ['ok' => true];` in a handler | empty response | `echo json_encode(['ok' => true]);` | | `fetch('', {method: 'POST', body: formData})` | no action found: the full HTML page comes back (200) | send JSON, or a backend endpoint for uploads | | Handler uses a variable set in the view script | undefined (handlers run first) | recompute in the handler or use a singleton | | `@AJAX('POST')` called with GET (or the reverse) | 405 | match the method | | Client calls a plain (non-`@AJAX`) function by `action` | falls through to the HTML page | mark it `@AJAX('POST')` | | Two handlers with the same name in different views | fatal redeclare | unique names app-wide | ## cscript | You write | What happens | Fix | |---|---|---| | `const name = "{{ $name }}";` | `""Ada""`: JS syntax error | `const name = {{ $name }};` | | `const n = {{ count($items) }};` | not converted: broken JS | `const n = ;` | ## Sessions and caching | You write | What happens | Fix | |---|---|---| | Writing `$_SESSION` in a view with `PHPUE_SESSION = 'lazy'` | lost for first-time visitors (no session yet) | `phpue_session(true)` before the write | | `session_start()` anywhere in the App script text (even a comment) | PHPue's session handling switches off | remove it; use `phpue_session()` | | Expecting nginx/CDN caching with default settings | every response sets a cookie and `no-store` | `PHPUE_SESSION = 'lazy'` | | A backend file that `return`s an array, loaded with `require_once` | second load returns `true`, not the array | folder with `autoload.php`, or `require` |