How to resolve unserialize(): Error at offset when loading PDF?

Question

Yii

I upload a PDF file with Cyrillic, then it comes out

PHP Notice yii\base\ErrorException with message unserialize(): Error at offset 5527 of 7876608 bytes in /var/www/www-root/data/www/2fraz.vadimtest.ru/vendor/yiisoft/yii2-debug/src/controllers/DefaultController.php:185

then 400 bad request.
Deleted the debug folder, didn't help.
The method referenced by the error

public function loadData($tag, $maxRetry = 0)
    {
        // retry loading debug data because the debug data is logged in shutdown function
        // which may be delayed in some environment if xdebug is enabled.
        // See: https://github.com/yiisoft/yii2/issues/1504
        for ($retry = 0; $retry <= $maxRetry; ++$retry) {
            $manifest = $this->getManifest($retry > 0);
            if (isset($manifest[$tag])) {
                $dataFile = $this->module->dataPath . "/$tag.data";
                $data = unserialize(file_get_contents($dataFile)); <----
                $exceptions = $data['exceptions'];
                foreach ($this->module->panels as $id => $panel) {
                    if (isset($data[$id])) {
                        $panel->tag = $tag;
                        $panel->load(unserialize($data[$id]));
                    }
                    if (isset($exceptions[$id])) {
                        $panel->setError($exceptions[$id]);
                    }
                }
                $this->summary = $data['summary'];

                return;
            }
            sleep(1);
        }

        throw new NotFoundHttpException("Unable to find debug data tagged with '$tag'.");
    }

Regular PDFs with images load fine.

Answer 1

$data = unserialize(file_get_contents($dataFile));
and then
you want to anserialize the anserialized? Steal what was stolen? Drink drunk?
But the error is rather unrelated to the pdf. 400 error is probably no csrf token.