After upgrading to 6.4.1 (give also errors) working further locally and trying again did solve for strange reasons. I am seeking still for a clear explanation for this issue for in case it happens again.
@Rapido; @Armando: Hi, It looks I resolved a similar ticket at the end of May and this specific forum was posted earlier in the month. https://forum.mendix.com/questions/16542/environmentjsonPRIVATE-DATA-HIDDEN-error The issue was fixed without any manual intervention, however It does look like there was either a database backup or sandbox maintenance occurring at that time, last month we had a high number of new sandboxes and deployments. Overall, we have most recently converted our sandboxes onto a new infrastructure which will not conflict with availability or cross-provisioning of particular sandbox maintenance occurrences. I am reaching out to see if you have seen this similar issue again? Please let us know by creating a support ticket at your convenience. Best regards, Michael Schlosser