Mendix 10 - next null error

Am I just having adventures like this or has everything suddenly started to go wrong at Mendix and everything is becoming a "black null series"?   I now have a problem with a really elementary thing.   I have, in simple terms, the relationship A <1 - *> B   I'm creating a page, with a parameter A where I want to display on the List View all the elements associated with B. There is nothing more. So far it is ok.   Now I place a button on the data view of entity A to call this page with parameter A and it gives me this error right after that: Do I have something broken in my Mendix or does version 10 work that badly?   If it works that badly, how do I move it to version 9.24? Is it possible to convert it?   What can I do to continue working? With all these errors it is becoming impossible and deadlines are pressing? :/
3 answers

Cannot help you solve this error. 


One tip; never start your project which needs to be release to production in a just released Major (or minor) version. Always us a LTS or MTS version of Studio pro. In this case the newest is 9.24.3


Answering your question can you downgrade it from 10 to 9.24…. No that’s not possible.

Only solution I do see is; rebuild it in 9.24.3 or stick with 10.0.0


Sorry to not really helping you :-/


Ok, I have found the only solution so far.

I exported the app package to a new file without data and imported it into Mendix 10 beta 2 and so far everything works.

I feel a bit sad about the test data I entered which allowed me to check the correctness of the functionality of the whole app, but trying to improt the app file with data into M10B2 resulted in a database incompatibility issue when compiling the site. 

So I would recommend, until Mendix 10 is fixed, going back to beta 2. (Going back to 9.24.3 unfortunately didn't work for me).


Hi Marc,


Downgrade mendix is tricky and risky thing to do.

If your project is fairly new and if you are in a position to take risk then you can give a try to “MprTool.exe” to change version.

Read this thread for more details →