Hello, is there some solution to this?
I have the same error here:
The website encountered an unexpected error. Please try again later.
TypeError: array_keys(): Argument #1 ($array) must be of type array, string given in array_keys() (line 313 of modules/xls_serialization/src/Encoder/Xls.php).
array_keys() (Line: 313)
Drupal\xls_serialization\Encoder\Xls->extractHeaders() (Line: 169)
Drupal\xls_serialization\Encoder\Xls->setHeaders() (Line: 75)
Drupal\xls_serialization\Encoder\Xls->encode() (Line: 40)
Symfony\Component\Serializer\Encoder\ChainEncoder->encode() (Line: 306)
Symfony\Component\Serializer\Serializer->encode() (Line: 129)
Symfony\Component\Serializer\Serializer->serialize() (Line: 77)
Drupal\serialization\EventSubscriber\DefaultExceptionSubscriber->on4xx() (Line: 112)
Drupal\Core\EventSubscriber\HttpExceptionSubscriberBase->onException()
call_user_func() (Line: 142)
Drupal\Component\EventDispatcher\ContainerAwareEventDispatcher->dispatch() (Line: 219)
Symfony\Component\HttpKernel\HttpKernel->handleThrowable() (Line: 91)
Symfony\Component\HttpKernel\HttpKernel->handle() (Line: 57)
Drupal\Core\StackMiddleware\Session->handle() (Line: 47)
Drupal\Core\StackMiddleware\KernelPreHandle->handle() (Line: 106)
Drupal\page_cache\StackMiddleware\PageCache->pass() (Line: 85)
Drupal\page_cache\StackMiddleware\PageCache->handle() (Line: 47)
Drupal\Core\StackMiddleware\ReverseProxyMiddleware->handle() (Line: 52)
Drupal\Core\StackMiddleware\NegotiationMiddleware->handle() (Line: 23)
Stack\StackedHttpKernel->handle() (Line: 717)
Drupal\Core\DrupalKernel->handle() (Line: 19)