Hello @Stefan Diestelmann

Typically, such errors in form inheritance indicate problems with components. Could you provide a minimal demo project of the main and inherited forms so we can reproduce this issue? No code from these forms is needed.

Thank you.

The Exceptiíon comes from the ide not the program, i can open any app in Rad Studio 13.1 if i open or create a TFgForm the Exception comes. may be from form designer.

Hi just for your information, i downgraded to 19.4.0 (to test it) and get same error opening Form Editors (May be it depends on Rad Studio 13.1 ?)

We need a minimal demo project to open it in the IDE and see the error that occurs.

9 hours ago, Stefan Diestelmann said:

Hi just for your information, i downgraded to 19.4.0 (to test it) and get same error opening Form Editors (May be it depends on Rad Studio 13.1 ?)

Hello Stephan,

Usually this type of error related to deserialization process and linked to a specific control on form. Unfortunately, this exception doesn't provide useful information about place and conditionals. So for reproducing we need to have unit form pas + xfm. In this case we can open this unit in debug mode and catch stack trace.

Sometimes it can be related to used assets. But it's rare case. So we can start from providing form unit. If you don't want to share it here, you can post me in direct message.

Thank you

Hello Yaroslav, i just created a new FGX App ann dooble clicked the main Form.

Exception comes.

Any Idea what i can test ?

For Test reason i disabled all my other vcl libs, only fgx left, but same exception comes

Did you install correct FGX Native designer form version in installer? Because Embarcadero broke compatibility between 13.0, 13.1, 13.2 versions.

There is no option for 13.1 only 12.3