Since the newest version of Ender IO, I have this crash:
"EnderIO: Found the following problem(s) with your installation: "An unsupportted old RF API is installed (1.7.10R1.0.1 from Railcraft_1.7.10-9.8.0.0.jar). Ender IO needs at least 1.7.10R1.0.2 and will NOT work with older versions." This may have caused the error. Try reproducing the crash WITHOUT this/these mod(s) before reporting it."

So, can You (The author of Railcraft) update the RF API?

Hmm...I am rather confused here. It appears that my dev environment has been set to use 1.7.10R1.0.2 since February. But you are correct, 9.8 shipped with 1.7.10R1.0.1. I have no idea how that is possible, especially considering I had to create a new dev environment from scratch in June.

Problem located.

Despite having the latest version of the RF API in my dev env, I also had an outdated version of Buildcraft. Gradle was pulling the RF API from the Buildcraft jar instead of the source files. Updating Buildcraft has fixed the issue.

I was just about to report this issue. I came across this exact error a moment ago - it wasn't Railcraft that caused the issue for my crash but I always read my crash logs fully

I've seen that approx 7 hours ago it was fixed via a commit 👍

I also have the same problem about how astronomy space ftb resolve sorry for my english google translation thank you. * WailaAPI (1.2) from Waila-1.5.10_1.7.10.jar
EnderIO: Found the following problem(s) with your installation: "An unsupportted old RF API is installed (1.7.10R1.0.1 from Railcraft_1.7.10-9.8.0.0.jar). Ender IO needs at least 1.7.10R1.0.2 and will NOT work with older versions." This may have caused the error. Try reproducing the crash WITHOUT this/these mod(s) before reporting it.

Wait until @CovertJaguar releases a new version @t4kumi

I have to wait myself as I cannot use the updated GitHub commits in a private modpack due to licencing.