Usually this error shows up when there are some invalid metadata in the schema. So for example a program indicator with an empty expression etc. Can you run an integrity check in Data Administration and try to fix any faulty metadata?
As @Karoline said, probably some metadata integrity error (and the integrity check is definitely worth a try). Could you post the log from the browser console? There might be a hint to what is wrong in there (Press Command+Option+J (Mac) or Control+Shift+J(Windows, Linux, Chrome OS) and then select the Console tab at the top if it is not already selected).
A couple of problems we’ve seen recently that could be the cause of this: 1) A data element is still present in a section, but is removed form the program stage itself. 2) A program indicator / program rule has an empty expression (as Karoline mentioned).
But if you could post the console log that would be great.
It seems to me that one of your relationshipTypes are missing either the fromConstraint or the toConstraint property. Could you investigate this? (using the maintenance app, the api or the database itself). Every relationshipType should have both a fromConstraint and a toConstraint.
Using the database, I would check that all the records in the relationshiptype table have their from_relationshipconstraintId and to_relationshipconstraintid set (and that those exist in the relationshipconstraint table).
If you don’t have too many relationship types, maybe it’s easier to click through them in the maintenance app though (open the maintenance app and navigate to the relationship type management and click through the entries until one of them gives you errors or are missing either the from constraint or the to constraint).
When you find the relationship type(s) with missing constraints, I would open them in the maintenance app and set the correct from- and to constraints.
If you can’t figure it out and you’re willing to share your relationship metadata, we can try to export the metadata for me (or someone else here) to have a look.