Thank you for the bug report. I've looked into this and found what is causing the issue.

The error is generated from php 8 on UBB.threads 8.0.x when attempting to read files/folders that are unreachable. If you are currently having issues and want to patch your install now, the fix is listed below.

in /admin/fileperms.php around line 150
FIND:
Code
foreach ($dirs as $k => $v) {
	$results[$v]['header'] = "<span style='color:green;'>OK</span>";
	$results[$v]['checks'] = "";
	$dir = @opendir("../$v");
	while ($file = @readdir($dir)) {
		if ($file == "..") {
			continue;
		}
		if (is_writeable("../$v/$file")) {
			$status = "<span style='color:green;'>OK</span>";
		} else {
			$status = "<span style='color:red;'>FAIL</span>";
			$results[$v]['header'] = "<span style='color:red;'>FAIL</span>";
		}
		if ($file == ".") {
			$file = "<b>&lt;DIRECTORY&gt;</b>";
		}
		$results[$v]['checks'] .= "<tr><td>$file</td><td>$status</td></tr>";
	}
}

REPLACE WITH
Code
foreach ($dirs as $k => $v) {
	$results[$v]['header'] = "<span style='color:green;'>OK</span>";
	$results[$v]['checks'] = "";
	$dir = "../$v";
	if ($handle = @opendir($dir)) {
		while (false !== ($file = @readdir($handle))) {
			if ($file == "..") {
				continue;
			}
			if (is_writeable("../$v/$file")) {
				$status = "<span style='color:green;'>OK</span>";
			}
			if ($file == ".") {
				$file = "<b>&lt;DIRECTORY&gt;</b>";
			}
			$results[$v]['checks'] .= "<tr><td>$file</td><td>$status</td></tr>";
		}
		closedir($handle);
	} else {
		$status = "<span style='color:red;'>FAIL</span>";
		$results[$v]['header'] = "<span style='color:red;'>FAIL</span>";
	}
}

You can manually apply this modification to your forums now, or wait until UBB.threads 8.1.0 is released when it will be included.

current developer of UBB.threads php forum software
current release: UBB.threads 8.0.1 // wip: UBB.threads 8.1.0
isaac @ id242.com // my forum @ CelicaHobby.com