diff --git a/common/framework/parsers/template/TemplateParser_v2.php b/common/framework/parsers/template/TemplateParser_v2.php
index cce065bd9..0486633f2 100644
--- a/common/framework/parsers/template/TemplateParser_v2.php
+++ b/common/framework/parsers/template/TemplateParser_v2.php
@@ -149,6 +149,7 @@ class TemplateParser_v2
 		$content = $this->_convertInlineDirectives($content);
 		$content = $this->_convertMiscDirectives($content);
 		$content = $this->_convertEchoStatements($content);
+		$content = $this->_addDeprecationMessages($content);
 
 		// Postprocessing.
 		$content = $this->_postprocess($content);
@@ -917,6 +918,31 @@ class TemplateParser_v2
 		}
 	}
 
+	/**
+	 * Add an error message if any supported v1 syntax is found.
+	 *
+	 * @param string $content
+	 * @return string
+	 */
+	protected function _addDeprecationMessages(string $content): string
+	{
+		// <block>
+		$content = preg_replace_callback('#<block(?=\s)#', function($match) {
+			return $match[0] . '<?php trigger_error("block element is not supported in template v2", \E_USER_WARNING); ?>';
+		}, $content);
+
+		// cond, loop
+		$content = preg_replace_callback('#(?<=\s)(cond|loop)="([^"]+)"#', function($match) {
+			if ($match[1] === 'loop' && ctype_alnum($match[2]))
+			{
+				return $match[0];
+			}
+			return '<?php trigger_error("' . $match[1] . ' attribute is not supported in template v2", \E_USER_WARNING); ?>';
+		}, $content);
+
+		return $content;
+	}
+
 	/**
 	 * Postprocessing.
 	 *
diff --git a/tests/unit/framework/parsers/TemplateParserV2Test.php b/tests/unit/framework/parsers/TemplateParserV2Test.php
index 937ec921d..2be9ea6f1 100644
--- a/tests/unit/framework/parsers/TemplateParserV2Test.php
+++ b/tests/unit/framework/parsers/TemplateParserV2Test.php
@@ -1057,6 +1057,43 @@ class TemplateParserV2Test extends \Codeception\Test\Unit
 		$this->assertEquals($target, $this->_parse($source));
 	}
 
+	public function testDeprecationMessages()
+	{
+		// <block> element
+		$source = '<block class="foobar">';
+		$target = '<block<?php trigger_error("block element is not supported in template v2", \E_USER_WARNING); ?> class="foobar">';
+		$this->assertEquals($target, $this->_parse($source));
+
+		// cond
+		$source = '<div cond="$foo->isBar()"></div>';
+		$target = '<div <?php trigger_error("cond attribute is not supported in template v2", \E_USER_WARNING); ?>></div>';;
+		$this->assertEquals($target, $this->_parse($source));
+
+		// cond is OK in includes
+		$source = '<include src="foo.html" cond="$bar" />';
+		$target = '<?php if(!empty($bar)): ?><?php $__tpl = new \Rhymix\Framework\Template($this->relative_dirname, "foo.html", "html"); echo $__tpl->compile(); ?><?php endif; ?>';;
+		$this->assertEquals($target, $this->_parse($source));
+
+		// loop
+		$source = '<tr loop="$foo => $bar"></tr>';
+		$target = '<tr <?php trigger_error("loop attribute is not supported in template v2", \E_USER_WARNING); ?>></tr>';;
+		$this->assertEquals($target, $this->_parse($source));
+
+		// loop is OK in multimedia elements
+		$source = '<video autoplay loop="loop"></video>';
+		$target = '<video autoplay loop="loop"></video>';
+		$this->assertEquals($target, $this->_parse($source));
+
+		// Comprehensive example
+		$source = '<block cond="$foo" loop="$arr => $k, $v"></block>';
+		$target = implode('', [
+			'<block<?php trigger_error("block element is not supported in template v2", \E_USER_WARNING); ?> ',
+			'<?php trigger_error("cond attribute is not supported in template v2", \E_USER_WARNING); ?> ',
+			'<?php trigger_error("loop attribute is not supported in template v2", \E_USER_WARNING); ?>></block>',
+		]);
+		$this->assertEquals($target, $this->_parse($source));
+	}
+
 	public function testCompile()
 	{
 		// General example