Magento 2 issues with layouts

 Hi 

I came with new issue debugging if have xml tag not valid issue to find which file it is.

Some times we will get xml errors like 

1 exception(s): Exception #0 (Magento\Framework\Config\Dom\ValidationException):
Element 'referenceBlock', attribute 'remove': 'True' is not a valid value of the atomic
type 'xs:boolean'. Line: 1 Element 'referenceBlock', attribute 'remove': 'True' is not
a valid value of the atomic type 'xs:boolean'. Line: 2 Element 'referenceBlock', attribute
'remove': 'True' is not a valid value of the atomic type 'xs:boolean'. Line: 3

like this of errors we will get It's hard find which file it is if we did in any xml file we can easily locate if some done long days ago if got ticket to solve this is hard to find. Some will do in pages admin Layout Update XML section some one done core files based their flexible they will do but finding is hard so for this do below steps we will get error code based on that we can search ang solve it
more info that might help resolve this by identifying the file at fault.
Edit vendor/magento/framework/Config/Dom.php
Or it might be lib/internal/Magento/Framework/Config/Dom.php depending on your installation of Magento.

Find the public function _initDom($xml)
And add something like this before the normal validation check.
$verboseOutput = true;
        if ($verboseOutput) {
          if ($this->validationState->isValidationRequired() && $this->schema) {
              $errors = $this->validateDomDocument($dom, $this->schema, $this->errorFormat);
              if (count($errors)) {
                  var_dump($errors);
                  $matches = [];
                 preg_match("/Line: (\\d+)/", $errors[count($errors)-1], $matches);
                 $lineNumber = intval($matches[1]);
                  $lines = explode("\n", $xml);
                  echo "<h1>A validation error occured in an XML layout file</h1>";
                  $lineText = htmlentities($lines[$lineNumber-1]);
                  echo $lineText . "<br>";
                 echo "<pre>";
                  echo "grep -rnw ./app -e " . escapeshellarg(trim($lineText));
                  echo "</pre>";
                  die('Please grep or search files for the above and fix it as per Magento 2 validation.');
              }
          }
        }
Before adding code :::
protected function _initDom($xml)
    {
        $dom = new \DOMDocument();
        $useErrors = libxml_use_internal_errors(true);
        $res = $dom->loadXML($xml);
         if (!$res) {
            $errors = self::getXmlErrors($this->errorFormat);
            libxml_use_internal_errors($useErrors);
            throw new \Magento\Framework\Config\Dom\ValidationException(implode("\n", $errors));
        }
        libxml_use_internal_errors($useErrors);
        if ($this->validationState->isValidationRequired() && $this->schema) {
            $errors = $this->validateDomDocument($dom, $this->schema, $this->errorFormat);
            if (count($errors)) {
                throw new \Magento\Framework\Config\Dom\ValidationException(implode("\n", $errors));
            }
        }
        return $dom;
    }

After Adding::
protected function _initDom($xml)
    {
        $dom = new \DOMDocument();
        $useErrors = libxml_use_internal_errors(true);
        $res = $dom->loadXML($xml);
        
        $verboseOutput = true;
        if ($verboseOutput) {
          if ($this->validationState->isValidationRequired() && $this->schema) {
              $errors = $this->validateDomDocument($dom, $this->schema, $this->errorFormat);
              if (count($errors)) {
                  var_dump($errors);
                  $matches = [];
                  preg_match("/Line: (\\d+)/", $errors[count($errors)-1], $matches);
                  $lineNumber = intval($matches[1]);
                  $lines = explode("\n", $xml);
                  echo "<h1>A validation error occured in an XML layout file</h1>";
                  $lineText = htmlentities($lines[$lineNumber-1]);
                  echo $lineText . "<br>";
                echo escapeshellarg(trim($lineText); 
                  die('Please grep or search files for the above and fix it as per Magento 2 validation.');
              }
          }
        }
        if (!$res) {
            $errors = self::getXmlErrors($this->errorFormat);
            libxml_use_internal_errors($useErrors);
            throw new \Magento\Framework\Config\Dom\ValidationException(implode("\n", $errors));
        }
        libxml_use_internal_errors($useErrors);
        if ($this->validationState->isValidationRequired() && $this->schema) {
            $errors = $this->validateDomDocument($dom, $this->schema, $this->errorFormat);
            if (count($errors)) {
                throw new \Magento\Framework\Config\Dom\ValidationException(implode("\n", $errors));
            }
        }
        return $dom;
    }
for me I got 
<referenceBlock name="aheadworks.blog.recent.posts" remove="True" />
I removed remove true tag then it working it is added under cmspages 
After fixing please remove code and save 
And add something like this before the normal validation check.