# Non-space characters found without seeing a doctype first. Expected “”.
> Canonical HTML version: https://rocketvalidator.com/html-validation/non-space-characters-found-without-seeing-a-doctype-first-expected-doctype-html
> Attribution: Rocket Validator (https://rocketvalidator.com)
> License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/)
The `` declaration is required by the HTML specification as the first non-whitespace content in any HTML document. It instructs the browser to render the page in **standards mode**, which means the browser follows modern CSS and HTML specifications faithfully. When the doctype is missing or preceded by other content, browsers fall back to **quirks mode** — a legacy rendering mode that emulates old browser behaviors and can cause inconsistent layout, box model differences, and other subtle bugs across browsers.
This error is triggered in several common scenarios:
- The `` declaration is completely absent from the file.
- Text, HTML tags, or other non-space characters appear before the doctype.
- A **Byte Order Mark (BOM)** or invisible characters were inadvertently inserted before the doctype by a text editor.
- Server-side code (such as PHP or template includes) outputs content before the doctype.
- An XML processing instruction like `` precedes the doctype (this is unnecessary in HTML5).
Beyond triggering quirks mode, a missing or misplaced doctype breaks standards compliance and can cause real-world rendering issues. For example, in quirks mode, `box-sizing` defaults differ, `table` elements don't inherit font sizes properly, and percentage-based heights may not resolve correctly. These problems can be difficult to debug because they only manifest in certain browsers or under specific conditions.
## How to Fix
1. **Open your HTML file** and make sure the very first line is `` with nothing before it — no whitespace characters, no text, no comments, and no BOM.
2. **Check for invisible characters.** If you copied content from another source or use a text editor that inserts a BOM, open the file in a hex editor or use your editor's "show invisible characters" feature to confirm nothing precedes the doctype.
3. **Check server-side scripts.** If you use PHP, ASP, or a templating engine, make sure no output (including blank lines or spaces outside script tags) is emitted before ``.
4. **Remove legacy doctypes or XML declarations.** In HTML5, the only doctype you need is ``. Older doctypes like `` are valid but unnecessary, and XML processing instructions should not be used in HTML documents.
## Examples
### Missing doctype
This document has no doctype at all, which triggers the error:
```html
My Page
Hello, world!
```
### Text before the doctype
Stray text or content before the declaration also triggers the error:
```html
Welcome to my site!
My Page
Hello, world!
```
### PHP output before the doctype
A common server-side issue where whitespace or output leaks before the doctype:
```php
My Page
Hello, world!
```
If `config.php` has a closing `?>` followed by a blank line, that blank line gets sent as output before the doctype. Ensure included files don't produce unintended output.
### Correct document
The doctype must be the absolute first thing in the file:
```html
My Page
Hello, world!
```
Note that the doctype declaration is case-insensitive — ``, ``, and `` are all valid. However, `` is the conventional form recommended by the HTML living standard. A single blank line or whitespace-only line before the doctype won't trigger this specific error (since the validator message specifies "non-space characters"), but it's best practice to avoid any content before the declaration to keep your document clean and unambiguous.