Undefined array key

[medarob]

Because of some wrong formated HTML (<ul> list element without <ul>, only <li>) we get the following warnings/errors: (TCPDF 6.11.2)

Core: Error handler (FE): PHP Warning: Undefined array key 0 in /var/www/typo3/vendor/tecnickcom/tcpdf/tcpdf.php line 20833
Core: Error handler (FE): PHP Warning: Undefined array key -1 in /var/www/typo3/vendor/tecnickcom/tcpdf/tcpdf.php line 20689
Core: Error handler (FE): PHP Warning: Undefined array key 0 in /var/www/typo3/vendor/tecnickcom/tcpdf/tcpdf.php line 19318

This patch seems to solve the issue.

--- a/tcpdf.php	2026-03-24 10:04:42.874321210 +0000
+++ b/tcpdf.php	2026-03-24 10:04:44.611931363 +0000
@@ -19315,7 +19315,7 @@
 				if ($key > 2) {
 					$this->addHTMLVertSpace($hbz, $hb, $cell, $firsttag);
 				}
-				if ($this->listordered[$this->listnum]) {
+				if (!empty($this->listordered[$this->listnum])) {
 					// ordered item
 					if (isset($parent['attribute']['type']) AND !TCPDF_STATIC::empty_string($parent['attribute']['type'])) {
 						$this->lispacer = $parent['attribute']['type'];
@@ -19326,6 +19326,9 @@
 					} else {
 						$this->lispacer = '#';
 					}
+					if (!isset($this->listcount[$this->listnum])) {
+						$this->listcount[$this->listnum] = 0;
+					}
 					++$this->listcount[$this->listnum];
 					if (isset($tag['attribute']['value'])) {
 						$this->listcount[$this->listnum] = intval($tag['attribute']['value']);
@@ -20686,7 +20689,7 @@
 		} elseif ($listtype == '!') {
 			// set default list type for unordered list
 			$deftypes = array('disc', 'circle', 'square');
-			$listtype = $deftypes[($listdepth - 1) % 3];
+			$listtype = $deftypes[max(0, ($listdepth - 1) % 3)];
 		} elseif ($listtype == '#') {
 			// set default list type for ordered list
 			$listtype = 'decimal';
@@ -20769,7 +20772,7 @@
 			// $textitem
 			case '1':
 			case 'decimal': {
-				$textitem = $this->listcount[$this->listnum];
+				$textitem = $this->listcount[$this->listnum] ?? '';
 				break;
 			}
 			case 'decimal-leading-zero': {
@@ -20830,7 +20833,7 @@
 			}
 			*/
 			default: {
-				$textitem = $this->listcount[$this->listnum];
+				$textitem = $this->listcount[$this->listnum] ?? '';
 			}
 		}
 		if (!TCPDF_STATIC::empty_string($textitem)) {

[williamdes]

Could you open a pull-request with your patch ?
And post an example of your HTML ?

[medarob]

PHP Warning: Undefined array key 0 in /var/www/typo3_web-dev2/vendor/tecnickcom/tcpdf/tcpdf.php line 19318

Our wrong HTML looked something like this:

missing <ul>

<ul>
    <li>loren ipsum</li>
    <li>loren ipsum</li>
    <li>loren ipsum</li>
</ul>
<p>
    <li>loren ipsum</li>
<br><br>loren ipsum<br><br>
</p>

<p>loren ipsum<br><br>loren ipsum<br>
    <li>loren ipsum</li>
    <li>loren ipsum</li>
    <li>loren ipsum</li>
    <li>loren ipsum</li>
    <li>loren ipsum</li>
    <li>loren ipsum</li>
    <br>loren ipsum<br>....
</p>

Correcting the syntax also worked and the error is gone. But that was expected and is probably the best solution but I will create a PR,

[medarob]

PR created: #860