Hello Andrew,

I have been investigating into the requirement to run different versions of Infragistics simultaneously, and while this may in theory be possible, it’s generally not a good idea as you will run into dependency issues. If at all possible, I would recommend normalization of the assembly versions that your project is targeting.

If you must use multiple versions of Infragistics in your application, the best thing I can then recommend is that you move all 13.1 targets to a single project and then all 18.1 stuff to another project so that you can isolate which versions are used in which places. Referencing these projects from another project that uses the forms and controls that you define may work after doing this.

Still though, I will reiterate that if at all possible, you should normalize the assembly versions in your application when using Infragistics controls.

Please let me know if you have any other questions or concerns on this matter.