when starting the game there are conflict with other mods

for example:

The game crashed whilst initializing game
Error: java.lang.NullPointerException: Cannot invoke "net.coderbot.iris.pipeline.PipelineManager.getPipeline()" because the return value of "net.coderbot.iris.Iris.getPipelineManager()" is null

Please open a new issue and fill out the form correctly. This message tells me nothing, at least attach the full logs.