cgartner-redstage/upgradeData.php

## upgradeData.php
<?php

use Magento\Cms\Model\Block;
use Magento\Cms\Model\BlockRepository;
use Magento\Cms\Model\BlockFactory;

// contruct
public function __construct(
    BlockRepository $blockRepository,
    BlockFactory $blockFactory
)
{
    $this->blockRepository = $blockRepository;
    $this->blockFactory = $blockFactory;
}

// code

$block = $this->blockFactory->create();
$block->setIdentifier('indentifier');

$html = <<<HTML
// html code
HTML;

$block->setTitle('Block name');
$block->setContent($html);
$block->setIsActive(true);
$block->setStoreId([0]); // 0 is for all stores

$this->blockRepository->save($block);
	<?php

	use Magento\Cms\Model\Block;
	use Magento\Cms\Model\BlockRepository;
	use Magento\Cms\Model\BlockFactory;

	// contruct
	public function __construct(
	BlockRepository $blockRepository,
	BlockFactory $blockFactory
	)
	{
	$this->blockRepository = $blockRepository;
	$this->blockFactory = $blockFactory;
	}

	// code

	$block = $this->blockFactory->create();
	$block->setIdentifier('indentifier');

	$html = <<<HTML
	// html code
	HTML;

	$block->setTitle('Block name');
	$block->setContent($html);
	$block->setIsActive(true);
	$block->setStoreId([0]); // 0 is for all stores

	$this->blockRepository->save($block);