Hi Iserena,
thanks for reaching out.
The critical bug causing fatal errors after updating to version 1.30.0 was solved with version 1.30.1.
I am not aware of new issues causing a crash using this latest version.
To make the site work again in such cases, you can temporarily rename advanced-ads folder (wp-content/plugins/advanced-ads) via FTP. This will disable the plugin in question, and you can safely roll back to an earlier version.
At the end of this page you can download the last versions of Advanced Ads if you feel more comfortable using version 1.29.1 for now:
https://wordpress.org/plugins/advanced-ads/advanced/
If you stumble about any further problems, please let me know. Please also provide information about the error message you encounter.
Best regards,
Henning