I decided to upgrade my web server containers to PHP 7 but ran into a problem with WordPress, all articles had no text. The problem seemed to be within the plugin CodeColorer since disabling it resolved the problem

PHP Warning:  preg_replace(): The /e modifier is no longer supported, use preg_replace_callback instead in /var/www/wp-content/plugins/codecolorer/codecolorer-core.php on line 50

In wp-content/plugins/codecolorer/codecolorer-core.php locate this code block:

  /** Search content for code tags and replace it */
  function BeforeHighlightCodeBlock($content) {
    $content = preg_replace('#(\s*)\[cc([^\s\]_]*(?:_[^\s\]]*)?)([^\]]*)\](.*?)\[/cc\2\](\s*)#sie', '$this->PerformHighlightCodeBlock(\'\\4\', \'\\3\', $content, \'\\2\', \'\\1\', \'\\5\');', $content);
    $content = preg_replace('#(\s*)\<code(.*?)\>(.*?)\</code\>(\s*)#sie', '$this->PerformHighlightCodeBlock(\'\\3\', \'\\2\', $content, \'\', \'\\1\', \'\\4\');', $content);

    return $content;
  }

and replace it with this

  /** Search content for code tags and replace it */
  function BeforeHighlightCodeBlock($content) {
    $content = preg_replace_callback('#(\s*)\[cc([^\s\]_]*(?:_[^\s\]]*)?)([^\]]*)\](.*?)\[/cc\2\](\s*)#si', function($matches){
      return $this->PerformHighlightCodeBlock($matches[4], $matches[3], $matches[2], $matches[1], $matches[5]);
    }, $content);
    $content = preg_replace_callback('#(\s*)\<code(.*?)\>(.*?)\</code\>(\s*)#si', function($matches){
      return $this->PerformHighlightCodeBlock($matches[3], $matches[2], '', $matches[1], $matches[4]);
    }, $content);

    return $content;
  }

It would of course make sense to find a replacement for CodeColorer since it does not seem to be maintained but that would probably also mean having to edit all old articles.