The following notes and warnings highlight missing or conflicting information which caused the validator to perform some guesswork prior to validation. If the guess or fallback is incorrect, it could make validation results entirely incoherent. It is highly recommended to check these potential issues, and, if necessary, fix them and re-validate the document.
No Character Encoding Found!
Falling back to
UTF-8
.
None of the standards sources gave any information on the character encoding
labeling for this document. Without encoding information
it is impossible to reliably validate the document. As a fallback
solution, the "UTF-8
"
encoding was used to read the content and attempt to perform the validation,
but this is likely to fail for all non-trivial documents.
The sources used to find encoding information include:
The algorithm defined in Appendix F of the XML 1.0 Recommendation was also used, without success.
Since none of these sources yielded any usable information, reliable validation of this document is not possible. Sorry. Please make sure you specify the character encoding in use.
Specifying a character encoding is typically done by the web server configuration, by the scripts that put together pages, or inside the document itself. IANA maintains the list of official names for character encodings (called charsets in this context). You can choose from a number of encodings, though we recommend UTF-8 as particularly useful.
The W3C I18N Activity has collected a few tips on how to declare the encoding of a Web document.
To quickly check whether the document would validate after addressing the missing character encoding information, you can use the "Encoding" form control earlier in the page to force an encoding override to take effect. "iso-8859-1" (Western Europe and North America) and "utf-8" (Universal, but not commonly used in legacy documents) are common encodings if you are not sure what encoding to choose.
Unable to Determine Parse Mode!
The validator can process documents either as XML (for document types such as XHTML, SVG, etc.) or SGML (for HTML 4.01 and prior versions). For this document, the information available was not sufficient to determine the parsing mode unambiguously, because:
text/html
) can be used for XML or SGML document types<?xml version="1.0"?>
) could be found at the beginning of the document.<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en">
) could be found at the root of the document.As a default, the validator is falling back to SGML mode.
No
DOCTYPE
found! Checking with default HTML 4.01 Transitional Document Type.
No DOCTYPE Declaration could be found or recognized in this document. This generally means that the document is not declaring its Document Type at the top. It can also mean that the DOCTYPE declaration contains a spelling error, or that it is not using the correct syntax.
The document was checked using a default "fallback" Document Type Definition that closely resembles “HTML 4.01 Transitional”.
It is recommended to use a DOCTYPE declaration as the very first thing in your HTML document, to identify the precise language being used. For example, for a typical XHTML 1.0 document:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" lang="en" xml:lang="en"> <head> <title>Title</title> </head> <body> <!-- ... body of document ... --> </body> </html>
For XML documents, you may also wish to include an "XML Declaration" even before the DOCTYPE Declaration, but this is not well supported in older browsers. More information about this can be found in the XHTML 1.0 Recommendation.
The W3C QA Activity maintains a List of Valid Doctypes that you can choose from, and the WDG maintains a document on "Choosing a DOCTYPE".
No Character encoding declared at document level
No character encoding information was found within the document, either in an HTML meta
element or an XML declaration. It is often recommended to declare the
character encoding in the document itself, especially if there is a
chance that the document will be read from or saved to disk, CD, etc.
See this tutorial on character encoding for techniques and explanations.
<html>
The checked page did not contain a document type ("DOCTYPE") declaration. The Validator has tried to validate with a fallback DTD, but this is quite likely to be incorrect and will generate a large number of incorrect error messages. It is highly recommended that you insert the proper DOCTYPE declaration in your document -- instructions for doing this are given above -- and it is necessary to have this declaration before the page can be declared to be valid.
<frameset cols="300,*">
You have used the attribute named above in your document, but the document type you are using does not support that attribute for this element. This error is often caused by incorrect use of the "Strict" document type with a document that uses frames (e.g. you must use the "Transitional" document type to get the "target" attribute), or by using vendor proprietary extensions such as "marginheight" (this is usually fixed by using CSS to achieve the desired effect instead).
This error may also result if the element itself is not supported in the document type you are using, as an undefined element will have no supported attributes; in this case, see the element-undefined error message for further information.
How to fix: check the spelling and case of the element and attribute, (Remember XHTML is all lower-case) and/or check that they are both allowed in the chosen document type, and/or use CSS instead of this attribute. If you received this error when using the <embed> element to incorporate flash media in a Web page, see the FAQ item on valid flash.
<frameset cols="300,*">
You have used the element named above in your document, but the document type you are using does not define an element of that name. This error is often caused by:
<frame name="_nav_frame" src="nav.php">
You have used the attribute named above in your document, but the document type you are using does not support that attribute for this element. This error is often caused by incorrect use of the "Strict" document type with a document that uses frames (e.g. you must use the "Transitional" document type to get the "target" attribute), or by using vendor proprietary extensions such as "marginheight" (this is usually fixed by using CSS to achieve the desired effect instead).
This error may also result if the element itself is not supported in the document type you are using, as an undefined element will have no supported attributes; in this case, see the element-undefined error message for further information.
How to fix: check the spelling and case of the element and attribute, (Remember XHTML is all lower-case) and/or check that they are both allowed in the chosen document type, and/or use CSS instead of this attribute. If you received this error when using the <embed> element to incorporate flash media in a Web page, see the FAQ item on valid flash.
<frame name="_nav_frame" src="nav.php">
You have used the attribute named above in your document, but the document type you are using does not support that attribute for this element. This error is often caused by incorrect use of the "Strict" document type with a document that uses frames (e.g. you must use the "Transitional" document type to get the "target" attribute), or by using vendor proprietary extensions such as "marginheight" (this is usually fixed by using CSS to achieve the desired effect instead).
This error may also result if the element itself is not supported in the document type you are using, as an undefined element will have no supported attributes; in this case, see the element-undefined error message for further information.
How to fix: check the spelling and case of the element and attribute, (Remember XHTML is all lower-case) and/or check that they are both allowed in the chosen document type, and/or use CSS instead of this attribute. If you received this error when using the <embed> element to incorporate flash media in a Web page, see the FAQ item on valid flash.
<frame name="_nav_frame" src="nav.php">
You have used the element named above in your document, but the document type you are using does not define an element of that name. This error is often caused by:
<frame name="_content_frame" src="startup.php">
You have used the element named above in your document, but the document type you are using does not define an element of that name. This error is often caused by:
</html>
Most likely, you nested tags and closed them in the wrong order. For example <p><em>...</p> is not acceptable, as <em> must be closed before <p>. Acceptable nesting is: <p><em>...</em></p>
Another possibility is that you used an element which requires a child element that you did not include. Hence the parent element is "not finished", not complete. For instance, in HTML the <head> element must contain a <title> child element, lists (ul, ol, dl) require list items (li, or dt, dd), and so on.