Problem with the sidebar position when adding a pagination ()

Clearly a bug 🙁

I’ve searched around and can’t figure anything out either. If you look at Firebug rather than the source, it gives slightly better indenting. The correct, page 1, coding looks like this (I left out the end divs in the hope that the spacing and line-breaks show it better):

<div class="container" role="main">

   <div class="row">

      <div class="span9 article-container">
         <article id="post-1169" class="post-1169 post type-post status-publish format-standard hentry category-histoire-du-quartier row-fluid">
         <div id="comments" class="comments-area"> </div>
         <hr class="featurette-divider">
         <nav id="nav-below" class="navigation" role="navigation">
         <hr class="featurette-divider">

      <div class="span3 right tc-sidebar">

The incorrect, page 2, coding looks like this:

<div class="container" role="main">

   <div class="row">
      <div id="comments" class="comments-area"> </div>
      <hr class="featurette-divider">
      <nav id="nav-below" class="navigation" role="navigation">
      <hr class="featurette-divider">

   <div class="span9 article-container">
      <article id="post-1169" class="post-1169 post type-post status-publish format-standard hentry category-histoire-du-quartier row-fluid">

   <div class="span3 right tc-sidebar">

In the correct format, the (bootstrap) row contains the article (with navigation) and the sidebar, so they float next to each other horizontally. In the incorrect format, the article and the sidebar are outside the row (which contains the navigation), following it, so they are simply rendered one after the other, vertically.

Just a little hunch: what happens if you edit class-main-content.php and change:
if( $tc_i%2 == 0)
TO:
if( 0 == 0)
This will make your post-list such that the photo is always on the left, but it may also have an effect on other, unintended, “alternating” behaviour, which is what the above looks (vaguely) like to me. Then again, it may not…

Either way, let us know what happens.

cold it be that you are using html markup like divs etc (for instance for the ‘notes:’ section) in your page’s content which you break by inserting the <!--nextpage--> tag?
or is there a plugin involved?

what is the full content of that page when viewed with the ‘text’ setting of the page editor?

I don’t think there is any automatic way of fixing this; you will likely need to make sure not to break any html tags with your ‘nextpage’ tag (?)

does the problem persist if you temporarily switch to the default theme (Twenty Thirteen or Twenty Twelve)?
and/or if you temporarily deactivate all plugins?