diff --git a/.travis.yml b/.travis.yml
index d5edd686a..cc0860ca4 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -4,6 +4,7 @@ php:
     - 7.2
     - 7.3
     - 7.4
+    - 8.0snapshot
 
 env:
     - PHP_BIN=php
diff --git a/readme.md b/readme.md
index 938324787..93868db2c 100644
--- a/readme.md
+++ b/readme.md
@@ -41,8 +41,8 @@ composer require tracy/tracy
 Alternatively, you can download the whole package or [tracy.phar](https://github.com/nette/tester/releases) file.
 
 | Tracy | PHP | compatible with browsers
-|-----------|---------------|----------
-| Tracy 2.6 | PHP 7.1 – 7.4 | Chrome 49+, Firefox 45+, MS Edge 14+, Safari 10+ and iOS Safari 10.2+
+|-----------|-----------------|----------
+| Tracy 2.6 | PHP 7.1 – 8.0   | Chrome 49+, Firefox 45+, MS Edge 14+, Safari 10+ and iOS Safari 10.2+
 | Tracy 2.5 | PHP 5.4.4 – 7.3 | Chrome 49+, Firefox 45+, MS Edge 12+, Safari 10+ and iOS Safari 10.2+
 | Tracy 2.4 | PHP 5.4.4 – 7.2 | Chrome 29+, Firefox 28+, IE 11+ (except AJAX), MS Edge 12+, Safari 9+ and iOS Safari 9.2+
 
diff --git a/src/Tracy/Helpers.php b/src/Tracy/Helpers.php
index a3eff6eb5..2f352085e 100644
--- a/src/Tracy/Helpers.php
+++ b/src/Tracy/Helpers.php
@@ -166,7 +166,7 @@ public static function getSource(): string
 				. $_SERVER['REQUEST_URI'];
 		} else {
 			return 'CLI (PID: ' . getmypid() . ')'
-				. ': ' . implode(' ', array_map([self::class, 'escapeArg'], $_SERVER['argv']));
+				. (isset($_SERVER['argv']) ? ': ' . implode(' ', array_map([self::class, 'escapeArg'], $_SERVER['argv'])) : '');
 		}
 	}
 
@@ -188,7 +188,7 @@ public static function improveException(\Throwable $e): void
 			$message .= ", did you mean $hint()?";
 			$replace = ["$m[2](", "$hint("];
 
-		} elseif (preg_match('#^Undefined variable: (\w+)#', $message, $m) && !empty($e->context)) {
+		} elseif (preg_match('#^Undefined variable:? \$?(\w+)#', $message, $m) && !empty($e->context)) {
 			$hint = self::getSuggestion(array_keys($e->context), $m[1]);
 			$message = "Undefined variable $$m[1], did you mean $$hint?";
 			$replace = ["$$m[1]", "$$hint"];
@@ -200,7 +200,7 @@ public static function improveException(\Throwable $e): void
 			$message .= ", did you mean $$hint?";
 			$replace = ["->$m[2]", "->$hint"];
 
-		} elseif (preg_match('#^Access to undeclared static property: ([\w\\\\]+)::\$(\w+)#', $message, $m)) {
+		} elseif (preg_match('#^Access to undeclared static property:? ([\w\\\\]+)::\$(\w+)#', $message, $m)) {
 			$rc = new \ReflectionClass($m[1]);
 			$items = array_intersect($rc->getProperties(\ReflectionProperty::IS_PUBLIC), $rc->getProperties(\ReflectionProperty::IS_STATIC));
 			$hint = self::getSuggestion($items, $m[2]);
@@ -223,7 +223,7 @@ public static function improveException(\Throwable $e): void
 	/** @internal */
 	public static function improveError(string $message, array $context = []): string
 	{
-		if (preg_match('#^Undefined variable: (\w+)#', $message, $m) && $context) {
+		if (preg_match('#^Undefined variable:? \$?(\w+)#', $message, $m) && $context) {
 			$hint = self::getSuggestion(array_keys($context), $m[1]);
 			return $hint ? "Undefined variable $$m[1], did you mean $$hint?" : $message;
 
diff --git a/tests/Tracy/Debugger.autoloading.phpt b/tests/Tracy/Debugger.autoloading.phpt
index 7298172cc..95aa082b0 100644
--- a/tests/Tracy/Debugger.autoloading.phpt
+++ b/tests/Tracy/Debugger.autoloading.phpt
@@ -3,6 +3,7 @@
 /**
  * Test: Tracy\Debugger autoloading.
  * @outputMatch %A%: Declaration of B::test(%a?%) should be compatible %a% A::test() in %A%
+ * @phpVersion < 8
  */
 
 declare(strict_types=1);
diff --git a/tests/Tracy/Debugger.exception.html.phpt b/tests/Tracy/Debugger.exception.html.phpt
index f175fac98..206a140f2 100644
--- a/tests/Tracy/Debugger.exception.html.phpt
+++ b/tests/Tracy/Debugger.exception.html.phpt
@@ -44,5 +44,5 @@ function third($arg1)
 
 
 define('MY_CONST', 123);
-echo @$undefined;
+@hex2bin('a'); // E_WARNING
 first(10, 'any string');
diff --git a/tests/Tracy/Debugger.logSeverity.E_NOTICE.development.phpt b/tests/Tracy/Debugger.logSeverity.E_NOTICE.development.phpt
index 0292154a7..6210ea30d 100644
--- a/tests/Tracy/Debugger.logSeverity.E_NOTICE.development.phpt
+++ b/tests/Tracy/Debugger.logSeverity.E_NOTICE.development.phpt
@@ -17,7 +17,7 @@ require __DIR__ . '/../bootstrap.php';
 Debugger::enable(Debugger::DEVELOPMENT, getTempDir());
 Debugger::$logSeverity = E_NOTICE;
 
-$variable = $missingVariable;
+$variable = &pi();
 
 Assert::count(0, glob(getTempDir() . '/exception*.html'));
 Assert::count(0, glob(getTempDir() . '/error.log'));
diff --git a/tests/Tracy/Debugger.logSeverity.E_NOTICE.phpt b/tests/Tracy/Debugger.logSeverity.E_NOTICE.phpt
index 95376619c..26b058141 100644
--- a/tests/Tracy/Debugger.logSeverity.E_NOTICE.phpt
+++ b/tests/Tracy/Debugger.logSeverity.E_NOTICE.phpt
@@ -17,9 +17,9 @@ require __DIR__ . '/../bootstrap.php';
 Debugger::enable(Debugger::PRODUCTION, getTempDir());
 Debugger::$logSeverity = E_NOTICE;
 
-$variable = $missingVariable;
+$variable = &pi();
 
-Assert::same('Undefined variable: missingVariable', error_get_last()['message']);
+Assert::same('Only variables should be assigned by reference', error_get_last()['message']);
 
 Assert::count(1, glob(getTempDir() . '/exception*.html'));
 Assert::count(1, glob(getTempDir() . '/error.log'));
diff --git a/tests/Tracy/Debugger.logging.warnings.phpt b/tests/Tracy/Debugger.logging.warnings.phpt
index 6e7f42283..bb2e60861 100644
--- a/tests/Tracy/Debugger.logging.warnings.phpt
+++ b/tests/Tracy/Debugger.logging.warnings.phpt
@@ -24,7 +24,7 @@ Debugger::enable(Debugger::PRODUCTION, $logDirectory, 'admin@example.com');
 
 
 // throw error
-$a++;
+hex2bin('a'); // E_WARNING
 
-Assert::match('%a%PHP Notice: Undefined variable: a in %a%', file_get_contents($logDirectory . '/error.log'));
+Assert::match('%a%PHP Warning: hex2bin(): Hexadecimal input string must have an even length in %a%', file_get_contents($logDirectory . '/error.log'));
 Assert::true(is_file($logDirectory . '/email-sent'));
diff --git a/tests/Tracy/Debugger.scream.phpt b/tests/Tracy/Debugger.scream.phpt
index 025c02fe5..27c4b1676 100644
--- a/tests/Tracy/Debugger.scream.phpt
+++ b/tests/Tracy/Debugger.scream.phpt
@@ -19,7 +19,6 @@ header('Content-Type: text/plain; charset=utf-8');
 
 Debugger::enable();
 
-@mktime(); // E_DEPRECATED
-@$x++; // E_NOTICE
-@min(1); // E_WARNING
+@$x = &pi(); // E_NOTICE
+@hex2bin('a'); // E_WARNING
 @require __DIR__ . '/fixtures/E_COMPILE_WARNING.php'; // E_COMPILE_WARNING (not working)
diff --git a/tests/Tracy/Debugger.shut-up.warnings.phpt b/tests/Tracy/Debugger.shut-up.warnings.phpt
index 291d63943..868092a67 100644
--- a/tests/Tracy/Debugger.shut-up.warnings.phpt
+++ b/tests/Tracy/Debugger.shut-up.warnings.phpt
@@ -18,7 +18,6 @@ header('Content-Type: text/plain; charset=utf-8');
 
 Debugger::enable();
 
-@mktime(); // E_DEPRECATED
-@$x++; // E_NOTICE
-@min(1); // E_WARNING
+@$x = &pi(); // E_NOTICE
+@hex2bin('a'); // E_WARNING
 @require __DIR__ . '/fixtures/E_COMPILE_WARNING.php'; // E_COMPILE_WARNING
diff --git a/tests/Tracy/Debugger.strict.console.phpt b/tests/Tracy/Debugger.strict.console.phpt
index 2bf1f17e0..3fdef5d86 100644
--- a/tests/Tracy/Debugger.strict.console.phpt
+++ b/tests/Tracy/Debugger.strict.console.phpt
@@ -36,7 +36,7 @@ function second($arg1, $arg2)
 
 function third($arg1)
 {
-	$x++;
+	$x = &pi();
 }
 
 
diff --git a/tests/Tracy/Debugger.strict.html.phpt b/tests/Tracy/Debugger.strict.html.phpt
index fbe5552bf..1e77f05fc 100644
--- a/tests/Tracy/Debugger.strict.html.phpt
+++ b/tests/Tracy/Debugger.strict.html.phpt
@@ -40,7 +40,7 @@ function second($arg1, $arg2)
 
 function third($arg1)
 {
-	$x++;
+	$x = &pi();
 }
 
 
diff --git a/tests/Tracy/Debugger.warnings.console.phpt b/tests/Tracy/Debugger.warnings.console.phpt
index 594239083..66a31b3af 100644
--- a/tests/Tracy/Debugger.warnings.console.phpt
+++ b/tests/Tracy/Debugger.warnings.console.phpt
@@ -34,20 +34,17 @@ function second($arg1, $arg2)
 
 function third($arg1)
 {
-	mktime(); // E_DEPRECATED
-	$x++; // E_NOTICE
-	min(1); // E_WARNING
+	$x = &pi(); // E_NOTICE
+	hex2bin('a'); // E_WARNING
 	require __DIR__ . '/fixtures/E_COMPILE_WARNING.php'; // E_COMPILE_WARNING
 }
 
 
 first(10, 'any string');
 Assert::match("
-Deprecated: mktime(): You should be using the time() function instead in %a% on line %d%
+Notice: Only variables should be assigned by reference in %a% on line %d%
 
-Notice: Undefined variable: x in %a% on line %d%
-
-Warning: %a% in %a% on line %d%
+Warning: hex2bin(): Hexadecimal input string must have an even length in %a% on line %d%
 
 Warning: Unsupported declare 'foo' in %a% on line %d%
 ", ob_get_clean());
diff --git a/tests/Tracy/Debugger.warnings.html.phpt b/tests/Tracy/Debugger.warnings.html.phpt
index 91ebf8c99..dd0bd6c83 100644
--- a/tests/Tracy/Debugger.warnings.html.phpt
+++ b/tests/Tracy/Debugger.warnings.html.phpt
@@ -36,15 +36,11 @@ Warning: Unsupported declare \'foo\' in %a% on line %d%%A%', $output);
 	Assert::match('%A%<table class="tracy-sortable">
 <tr>
 	<td class="tracy-right">1%a%</td>
-	<td><pre>PHP Deprecated: mktime(): You should be using the time() function instead in %a%:%d%</a></pre></td>
+	<td><pre>PHP Notice: Only variables should be assigned by reference in %a%:%d%</a></pre></td>
 </tr>
 <tr>
 	<td class="tracy-right">1%a%</td>
-	<td><pre>PHP Notice: Undefined variable: x in %a%:%d%</a></pre></td>
-</tr>
-<tr>
-	<td class="tracy-right">1%a%</td>
-	<td><pre>PHP Warning: %a% in %a%:%d%</a></pre></td>
+	<td><pre>PHP Warning: hex2bin(): Hexadecimal input string must have an even length in %a%:%d%</a></pre></td>
 </tr>
 </table>
 </div>%A%', $panelContent);
@@ -66,9 +62,8 @@ function second($arg1, $arg2)
 
 function third($arg1)
 {
-	mktime(); // E_DEPRECATED
-	$x++; // E_NOTICE
-	min(1); // E_WARNING
+	$x = &pi(); // E_NOTICE
+	hex2bin('a'); // E_WARNING
 	require __DIR__ . '/fixtures/E_COMPILE_WARNING.php'; // E_COMPILE_WARNING
 }
 
diff --git a/tests/Tracy/Debugger.warnings.production.phpt b/tests/Tracy/Debugger.warnings.production.phpt
index 77f01805e..43d9d1001 100644
--- a/tests/Tracy/Debugger.warnings.production.phpt
+++ b/tests/Tracy/Debugger.warnings.production.phpt
@@ -17,7 +17,6 @@ Debugger::$productionMode = true;
 
 Debugger::enable();
 
-mktime(); // E_DEPRECATED
-$x++; // E_NOTICE
-min(1); // E_WARNING
+$x = &pi(); // E_NOTICE
+hex2bin('a'); // E_WARNING
 require __DIR__ . '/fixtures/E_COMPILE_WARNING.php'; // E_COMPILE_WARNING
diff --git a/tests/Tracy/Helpers.improveException.phpt b/tests/Tracy/Helpers.improveException.phpt
index 4f0dd622a..92fa94fc2 100644
--- a/tests/Tracy/Helpers.improveException.phpt
+++ b/tests/Tracy/Helpers.improveException.phpt
@@ -173,7 +173,7 @@ test(function () use ($obj) { // suggest only static property
 	} catch (\Error $e) {
 	}
 	Helpers::improveException($e);
-	Assert::same('Access to undeclared static property: TestClass::$publicStaticX, did you mean $publicStatic?', $e->getMessage());
+	Assert::match('Access to undeclared static property%a?% TestClass::$publicStaticX, did you mean $publicStatic?', $e->getMessage());
 	Assert::match('editor://fix/?file=%a%Helpers.improveException.phpt&line=%d%&search=%3A%3A%24publicStaticX&replace=%3A%3A%24publicStatic', $e->tracyAction['link']);
 	Assert::same('fix it', $e->tracyAction['label']);
 });
@@ -184,7 +184,7 @@ test(function () use ($obj) { // suggest only public static property
 	} catch (\Error $e) {
 	}
 	Helpers::improveException($e);
-	Assert::same('Access to undeclared static property: TestClass::$protectedMethodX', $e->getMessage());
+	Assert::match('Access to undeclared static property%a?% TestClass::$protectedMethodX', $e->getMessage());
 	Assert::false(isset($e->tracyAction));
 });
 
diff --git a/tests/Tracy/PHP.errorHandler.phpt b/tests/Tracy/PHP.errorHandler.phpt
deleted file mode 100644
index 5b6548c81..000000000
--- a/tests/Tracy/PHP.errorHandler.phpt
+++ /dev/null
@@ -1,21 +0,0 @@
-<?php
-
-/**
- * Test: PHP error handler.
- */
-
-declare(strict_types=1);
-
-use Tester\Assert;
-
-
-require __DIR__ . '/../bootstrap.php';
-
-
-// ensure trigger_error works as expected
-set_error_handler(function ($severity, $message, $file, $line, $context) {
-	Assert::same(10, $context['var']);
-});
-
-$var = 10;
-trigger_error('Ahoj', E_USER_ERROR);
diff --git a/tests/Tracy/expected/Debugger.error-in-eval.expect b/tests/Tracy/expected/Debugger.error-in-eval.expect
index 3cdf4911d..ece26e4c0 100644
--- a/tests/Tracy/expected/Debugger.error-in-eval.expect
+++ b/tests/Tracy/expected/Debugger.error-in-eval.expect
@@ -59,7 +59,7 @@
 						<tr><th>$message</th><td><pre class="tracy-dump"><span class="tracy-dump-string">"The my error"</span> (%d%)
 </pre>
 </td></tr>
-<tr><th>$error_type</th><td><pre class="tracy-dump"><span class="tracy-dump-number">256</span>
+<tr><th>$error_%a%</th><td><pre class="tracy-dump"><span class="tracy-dump-number">256</span>
 </pre>
 </td></tr>
 						</table>
@@ -99,23 +99,7 @@
 										</li>
 									</ol>
 			</div></div>
-
-
-						<div class="panel">
-			<h2><a data-tracy-ref="^+" class="tracy-toggle tracy-collapsed">Variables</a></h2>
-
-			<div class="tracy-collapsed inner">
-			<div class="outer">
-			<table class="tracy-sortable">
-			<tr><th>$user</th><td><pre class="tracy-dump"><span class="tracy-dump-string">"root"</span> (4)
-</pre>
-</td></tr>
-<tr><th>$pass</th><td><pre class="tracy-dump"><span class="tracy-dump-string">"*****"</span> (5)
-</pre>
-</td></tr>
-			</table>
-			</div>
-			</div></div>
+%A%
 
 
 
diff --git a/tests/Tracy/expected/Debugger.exception.html.expect b/tests/Tracy/expected/Debugger.exception.html.expect
index a2405120e..f4595aa21 100644
--- a/tests/Tracy/expected/Debugger.exception.html.expect
+++ b/tests/Tracy/expected/Debugger.exception.html.expect
@@ -117,7 +117,7 @@
 		<h2><a data-tracy-ref="^+" class="tracy-toggle tracy-collapsed">Last muted error</a></h2>
 		<div class="tracy-collapsed inner">
 
-		<h3>Notice: Undefined variable: undefined</h3>
+		<h3>Warning: hex2bin(): Hexadecimal input string must have an even length</h3>
 					<p><a href="editor:%a%" title="%a%Debugger.exception.html.phpt:%d%">%a%<b>Debugger.exception.html.phpt</b>:%d%</a></p>
 			<div>%A%</div>
 
diff --git a/tests/Tracy/expected/Debugger.scream.expect b/tests/Tracy/expected/Debugger.scream.expect
index db3de6c92..58b6fc9f3 100644
--- a/tests/Tracy/expected/Debugger.scream.expect
+++ b/tests/Tracy/expected/Debugger.scream.expect
@@ -1,6 +1,4 @@
 
-Deprecated: mktime(): You should be using the time() function instead in %a% on line %d%
+Notice: Only variables should be assigned by reference in %a% on line %d%
 
-Notice: Undefined variable: x in %a% on line %d%
-
-Warning: %a% in %a% on line %d%
+Warning: hex2bin(): Hexadecimal input string must have an even length in %a% on line %d%
diff --git a/tests/Tracy/expected/Debugger.strict.console.expect b/tests/Tracy/expected/Debugger.strict.console.expect
index 67d8f4c52..9cdc3836a 100644
--- a/tests/Tracy/expected/Debugger.strict.console.expect
+++ b/tests/Tracy/expected/Debugger.strict.console.expect
@@ -1,6 +1,6 @@
-ErrorException: Undefined variable: x in %a%
+ErrorException: Only variables should be assigned by reference in %a%
 Stack trace:
-#0 %a%: Tracy\Debugger::errorHandler(8, '%a%', '%a%', %a%, Array)
+#0 %a%: Tracy\Debugger::errorHandler(8, '%a%', '%a%', %a%)
 #1 %a%: third(Array)
 #2 %a%: second(true, false)
 #3 %a%: first(10, 'any string')
diff --git a/tests/Tracy/expected/Debugger.strict.html.expect b/tests/Tracy/expected/Debugger.strict.html.expect
index 98fcf498f..a98636888 100644
--- a/tests/Tracy/expected/Debugger.strict.html.expect
+++ b/tests/Tracy/expected/Debugger.strict.html.expect
@@ -5,7 +5,7 @@
 	<meta name="robots" content="noindex">
 	<meta name="generator" content="Tracy by Nette Framework">
 
-	<title>Notice: Undefined variable: x</title>
+	<title>Notice: Only variables should be assigned by reference</title>
 	<!-- in %a%:%d% -->
 
 	%A%
@@ -19,7 +19,7 @@
 		<div id="tracy-bs-error" class="panel">
 			<p>Notice</p>
 
-			<h1><span>Undefined variable: x</span>
+			<h1><span>Only variables should be assigned by reference</span>
 						<a href="%a%" target="_blank" rel="noreferrer noopener">search&#x25ba;</a>
 			</h1>
 		</div>
@@ -106,20 +106,7 @@
 										</li>
 									</ol>
 			</div></div>
-
-
-						<div class="panel">
-			<h2><a data-tracy-ref="^+" class="tracy-toggle tracy-collapsed">Variables</a></h2>
-
-			<div class="tracy-collapsed inner">
-			<div class="outer">
-			<table class="tracy-sortable">
-			<tr><th>$arg1</th><td><pre class="tracy-dump" data-tracy-dump='[[0,1],[1,2],[2,3]]'></pre>
-</td></tr>%A?%
-			</table>
-			</div>
-			</div></div>
-
+%A%
 
 
 				<div class="panel">