Previous versions of document give 404 not found

Sometimes, unexplainable 404’s can be solved by resaving the Permalink Settings within WordPress.

This is not a permalink issue.
This is a question of the link to the file being wrong.

If you change the file type, all previous versions are assumed to have the same filetype – and then the links won’t work.

Why is it that when putting together the permalink that it can’t look on the mime-type and do the file ending from there? Or save the file ending in the post-meta, or even check the file that it links to and grab the file ending from there?

If you do not believe me, try it yourself – upload a .doc file, then upload a .xls file and finally a .pdf.

This is an issue that must be fixed.

I have traced this now to the function

function filename_rewrite( $file ) {

		//verify this is a document
		if ( !$this->verify_post_type( $_POST['post_id'] ) )
			return $file;

		//hash and replace filename, appending extension
		$file['name'] = md5( $file['name'] .time() ) . $this->get_extension( $file['name'] );

		$file = apply_filters( 'document_internal_filename', $file );

		return $file;

	}

in wp-document-revisions.php

$this->get_extension( $file['name'] ) seem to take the extension from the filename, and that filename is the name of the current version.

I am not a PHP-developer, but if anyone has a solution to this I would very much appreciate this.

Ok I believe what you are looking for is this:
Unfortunately there isn’t a filter or action I can just use, but here is the solution… hopefully Ben will add this in, because mime type and file extension mismatches are a problem for IE security settings and some proxy servers…

In the file:
\wp-content\plugins\wp-document-revisions\includes\admin.php
@line 405 just after the line that says: “continue;”

Add this code:

if(is_numeric($revision->post_content)){
	$fn = get_post_meta( $revision->post_content, '_wp_attached_file', true );
	$fno = pathinfo($fn);
	$info = pathinfo(get_permalink( $revision->ID ));
	$fn = $info['dirname'].'/'.$info['filename'].'.'.$fno['extension'];
	}else{ $fn = get_permalink( $revision->ID ); }

Then just below there you will find the code where the revisions list is generated…
Change
<td><a href="<?php echo get_permalink( $revision->ID ); ?>"
To
<td><a href="<?php echo $fn; ?>"

Then each revision link will have the proper extension.