Hi Catia,
Sorry for the inconvenience caused by the Server Incident. We recently received some feedback regarding this.
This issue was posted to the Service Health Dashboard (SHD) as incident
SP175429 or SP175430 starting at 2019-03-07 23:03 (UTC). The user experience of this incident is: Users are unable to edit workflows or create new workflows in SharePoint 2010 using Designer and other protocols.
More info: Users may receive the error: "Errors were found when compiling the workflow. The Workflow files were saved but cannot run." Tenant administrators can view current information and updates on SHD at the link here
https://portal.office.com/AdminPortal/Home#/servicehealth

If you are experiencing a similar issue and do not see an SHD post, please let us know by sharing your tenant information via
Private Message (PM) as this may indicate either a scoping issue or an independent problem.
For affected customers to easily identify the information here, this thread will be closed. You may subscribe to this thread or refer to SHD for updated information. I will also post back here once the issue is resolved on SHD.
Best Regards,
Eli