If you have too many items such as dataframes, charts etc. in the project, you may see the EMFILE: too many open files error when you open a project or do some operation in a project.
You can restart the Exploratory Desktop, open the project, and remove unnecessary items from the project to avoid this problem.
If you are using Mac, you can also increase the “max open files” system setting by running a system command such as sysctl from the command line. The command may vary depending on which MacOS version you are using. Please check out the system manual for the detail.