Error 'Cascade deleting too many records' when you bulk delete Campaign records

Warning: Always back up your data before performing any data operation. See Export Backup Data from Salesforce or Export Data for more details. It is recommended to run a test with a small subset of records to confirm the operation was successful before proceeding with the full dataset.
Solution 1: Lower the Data Loader Batch Size to 1
The preferred solution is to lower the batch size in Data Loader settings to 1. This allows Data Loader to delete one parent Campaign record and its associated child records at a time, reducing the likelihood of triggering the cascade delete threshold.

1. Open Data Loader.
2. Select Settings > Settings.
3. Change the Batch Size to 1.
4. Click Save.
5. Retry the Campaign mass delete.

Note: If there is a very high number of child records associated with the deleted parent, you may continue to receive the error even with a batch size of 1.
Solution 2: Delete Campaign Members First
Deleting the Campaign Members before deleting the Campaigns avoids triggering the cascade deletion of Campaign Members and their related objects.

1. Run a Campaign report that includes the Campaign ID and Campaign Member ID, filtered to display only the Campaign Members associated with the Campaigns to be deleted.
2. Export the report as a CSV file.
3. In Data Loader, select Delete > check Show all Salesforce objects > select Campaign Members.
4. Map the exported report ID to the Campaign Member ID field.
5. Once the Campaign Members are deleted, retry the Campaign mass delete.