Hey I tried a few times today to start up a new singleplayer game after picking up the new DLC. Opened the game fine, hit new game, went to start it after changing the settings, and it displayed the error message shown in the screenshot. Tried a few more times, twice after even verifying the cache through steam which were all met with the same error message. I've attached the diagnostics and other required files to this post. Diagnostics - 2019'05'25 @2138'05''.htmlf44a6c39373b56f4aaefb23ec5d11f8d.pngoutput_log.txtDxDiag.txt

Not a pro here, but I guess you have sandbox mod activated, what seems to cause trouble. Is your Windows up to date (there are some windows update errors reported)?

No sandbox mod and windows is up to date. However I believe I solved the issue by making the Endless Space 2 folder in documents not read-only. I appreciate the help though. 

Glad to hear you figured it out. The most common source of this issue is indeed a problem writing to the ES2 folder, sometimes because of permissions, sometimes antivirus software interfering, or even the one-drive synchronization.