You can’t revert back. You’ll have edit it. Look at the audit trail report, it may give you an idea of what was on the original invoice.

Resolution for 'active invoice issue: 'I accidentally made changes to active invoice and saved it. How do I revert back to it.' available: Yes.

The active invoice issue or error code is a known issue in Quickbooks Online (QBO) and/or Quickbooks. Support for this issue is available either by self-service or paid support options. Experts are available to resolve your Quickbooks issue to ensure minimal downtime and continue running your business. First try to resolve the active invoice issue yourself by looking for a resolution described in the article. If it is a complex active invoice issue or you are unable to solve the issue, you may contact us by clicking here or by using other active invoice support options.

For more information about resolving issues related to active invoice in Quickbooks/QBO or to get support for the issue 'I accidentally made changes to active invoice and saved it. How do I revert back to it.', click the link below: