# Errors > Every error message, what causes it and how to fix it. Vascula reports mistakes instead of rendering something wrong. Errors come from two phases: - **Compile errors** mean the source is malformed. They are found as soon as the template is saved, before any data is involved. - **Render errors** depend on the data: a name that is not allowed, a division by zero, a value that is too large. Messages end with the position, `(line L, col C)`, counting characters from 1, when one is known. In a child template the message starts with `{% render %} "name":` and the position is in the child's source. ## Compile errors ### {% x %} is never closed with {% endx %} A block tag (`if`, `unless`, `for`, `case`, `capture`, `form`, `comment`) has no matching end tag. The position is where the block opens. ```vascula ``` ```error {% for %} is never closed with {% endfor %} (line 1, col 5) ``` ### unexpected {% endx %} with no opening tag An end tag, `else`, `elsif` or `when` appears where no block is open, often because of a typo in the opening tag or an extra end tag. ```vascula {% if settings.a %}a{% endif %}{% endif %} ``` ```error unexpected {% endif %} with no opening tag ``` ### unknown tag "x" The tag is not part of Vascula and the application did not declare a host tag with that name. ```vascula {% includes "footer" %} ``` ```error unknown tag "includes" ``` ### expected X, found Y The tag or expression is malformed at that point. The message names what was expected and what was found. ```vascula {% assign total 5 %} ``` ```error expected "=", found number "5" (line 1, col 17) ``` ```vascula {{ product.title | }} ``` ```error expected name, found "}}" ``` ### unterminated ... A string, `{{`, `{%` or `{#` is never closed. Vascula refuses rather than treating the rest of the file as part of it. ```vascula

{{ "unclosed }}

``` ```error unterminated string ``` ### ... is reserved A name that cannot be bound was assigned, captured, used as a loop variable or passed to a child: `settings`, `forloop`, or a name the application reserved. Choose another name. ```vascula {% for forloop in (1..2) %}{% endfor %} ``` ```error for variable "forloop" is reserved ``` ### duplicate render argument ```vascula {% render "card", title: 1, title: 2 %} ``` ```error duplicate render argument "title" ``` ### {% render %} requires a literal template name The name after `render` must be a quoted string. ```vascula {% render settings.name %} ``` ```error requires a literal template name ``` ### the {% raw %} block is not available There is no way to print unescaped text from a template. See [Output](/output). ```vascula {% raw %}{% endraw %} ``` ```error the {% raw %} block is not available ``` ### {% form %} errors `{% form %}` needs a kind the application registered, and cannot set attributes the application controls (`action`, `method`, `enctype`). See [Extending: forms](/extending#forms). ### compile budget exceeded The source is larger, or nests deeper, than the compilation limits allow. See [Safety and limits](/safety#compilation-limits). ## Render errors ### undeclared name "x" The template read a name that is not a variable, not `settings`, not a global and not an allowed data root. Usually a typo, a missing `assign`, or data the template must ask the application to allow. ```vascula {{ customer.name }} ``` ```error undeclared name "customer": it is not a variable or an allowed data root (line 1, col 4) ``` The Go error is a `*vascula.UndeclaredNameError` with the name; see [Go API](/go-api#type-undeclarednameerror). ### unknown filter "x" No built-in or application filter has that name. ```vascula {{ "x" | upcse }} ``` ```error unknown filter "upcse" ``` ### filter "x": ... A filter rejected its input or arguments. The message says why. ```vascula {{ 10 | divided_by: 0 }} ``` ```error filter "divided_by": divided_by: division by zero ``` ```vascula {{ "tomorrow" | date: "%Y" }} ``` ```error date: cannot parse "tomorrow" as a date ``` ### filter "x" does not take a named argument "y" Built-in filters accept only the named arguments they document (only `default` has one: `allow_false`). This usually means a filter's arguments swallowed the next render argument; put the filtered argument last. See [Composition: arguments](/composition#arguments). ### cannot compare A and B with "op" `<`, `>`, `<=` and `>=` need two numbers or two strings. ```vascula {% if settings.count > "3" %}{% endif %} ``` ```json data {"settings": {"count": 5}} ``` ```error cannot compare number and string with ">" ``` ### {% break %} outside a for loop `break` and `continue` only work inside a loop. A child template cannot break its caller's loop. ```vascula {% break %} ``` ```error {% break %} outside a for loop ``` ### {% render %} ... A child could not be rendered. The message continues with the reason: the application's resolver refused the name, the child failed (with its own message and position), or children nested more than 32 levels deep, which usually means a template renders itself. ### {% form %}: host token missing The data root that holds the form token is missing or empty for this render. The application must supply it. ### render budget exceeded: ... The render reached one of the [rendering limits](/safety#rendering-limits): | Message ends with | Meaning | |---|---| | `too many steps` | Too much work: usually nested loops over large collections. | | `output too large` | The page would exceed the output limit. | | `value too large` | One value has more text than allowed. | | `too many value nodes` | One value has too many items. | | `value nesting too deep` | A value is nested more than 64 levels. | | `range too large` | A range has more items than allowed. | | `expression too deep` | An expression nests more than 256 levels. | Reduce the data or the work; raise a limit only if a real template needs it. ### non-finite numbers are not supported A value was infinite or not a number. Vascula refuses rather than printing `NaN`.