Notice: unserialize(): Error at offset ... of ... bytes ...
You can try this to unserialize a corrupted serialized string.
use Wizacode\ErrorProofUnserializer\ErrorProofUnserializer;
// Attempt to unserialize a corrupted serialized string:
$recoveredUnserializedData = ErrorProofUnserializer::process($brokenSerializedString);
// Or only fix the serialized string:
$fixedSerializedData = ErrorProofUnserialize::fix($brokenSerializedString);
P.S.: Don't record php serialized data in a RDBMS (or use at least a binary safe storage type)