Sponge has been updated Sponge1.8.9, I would like to ask the 1.8 server have to upgrade it? Some mod no 1.8.9 version. Is it necessary for me to upgrade?
Sponge1.8 will continue to update ?
Yes forge must be updated to 1.8.9.
SpongeForge for 1.8 will no longer receive updates and implementation changes. Forge as well has seemingly ceased development targeting 1.8, so most all mods are just making the jump to 1.8.9 as well.
Aside from the more obvious reasons including that 1.8.9 has a great many security fixes and such, there’s quite a few underlying changes in Forge that required updates to SpongeForge that aren’t backward compatible.