@rowey thanks! Ill have a look!

@blackyps got it! Thanks a lot

@sheikah Hi, thanks for the answer! That is probably because I was trying to make a mod myself and it doesn't have a UID since I don't know what is needed in that field. Do you happen to know where I could read up on that?

@rowey is there any chance we will get some kind of wiki entry for mod creation as well? Something that details the very basics such as where to get a UID from? I was trying to upload a "mod" (just a console command basically) but it says UID is missing and I have no idea what the requirements there are

@rowey if you go to the mods tab there is an upload button:

upon clicking and choosing a mod folder to upload, it opens a modal that has a button for the rules:

FAF client gives me the following error when I try to load mods.

java.util.concurrent.CompletionException: java.lang.IllegalStateException: java.lang.IllegalStateException: Duplicate key 4c6694bd-aaaa-aa12-8fe7-cf2c9e8e8889 (attempted merging values true and true)
at org.springframework.aop.interceptor.AsyncExecutionAspectSupport.lambda$doSubmit$3(AsyncExecutionAspectSupport.java:279)
at java.base/java.util.concurrent.CompletableFuture$AsyncSupply.run(CompletableFuture.java:1764)
at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1130)
at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:630)
at java.base/java.lang.Thread.run(Thread.java:832)
Caused by: java.lang.IllegalStateException: java.lang.IllegalStateException: Duplicate key 4c6694bd-aaaa-aa12-8fe7-cf2c9e8e8889 (attempted merging values true and true)
at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:64)
at java.base/jdk.internal.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.base/java.lang.reflect.Constructor.newInstanceWithCaller(Constructor.java:500)
at java.base/java.lang.reflect.Constructor.newInstance(Constructor.java:481)
at java.base/java.util.concurrent.ForkJoinTask.getThrowableException(ForkJoinTask.java:600)
at java.base/java.util.concurrent.ForkJoinTask.reportException(ForkJoinTask.java:678)
at java.base/java.util.concurrent.ForkJoinTask.invoke(ForkJoinTask.java:737)
at java.base/java.util.stream.ReduceOps$ReduceOp.evaluateParallel(ReduceOps.java:919)
at java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:233)
at java.base/java.util.stream.ReferencePipeline.collect(ReferencePipeline.java:578)
at com.faforever.client.mod.ModService.overrideActivatedMods(ModService.java:315)
at com.faforever.client.mod.ModService.updateAndActivateModVersions(ModService.java:437)
at com.faforever.client.mod.ModService$$FastClassBySpringCGLIB$$aae9cfd3.invoke(<generated>)
at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:218)
at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.invokeJoinpoint(CglibAopProxy.java:779)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:163)
at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.proceed(CglibAopProxy.java:750)
at org.springframework.aop.interceptor.AsyncExecutionInterceptor.lambda$invoke$0(AsyncExecutionInterceptor.java:115)
at org.springframework.aop.interceptor.AsyncExecutionAspectSupport.lambda$doSubmit$3(AsyncExecutionAspectSupport.java:276)
... 4 more
Caused by: java.lang.IllegalStateException: Duplicate key 4c6694bd-aaaa-aa12-8fe7-cf2c9e8e8889 (attempted merging values true and true)
at java.base/java.util.stream.Collectors.duplicateKeyException(Collectors.java:133)
at java.base/java.util.stream.Collectors.lambda$uniqKeysMapMerger$0(Collectors.java:155)
at java.base/java.util.stream.ReduceOps$3ReducingSink.combine(ReduceOps.java:174)
at java.base/java.util.stream.ReduceOps$3ReducingSink.combine(ReduceOps.java:160)
at java.base/java.util.stream.ReduceOps$ReduceTask.onCompletion(ReduceOps.java:959)
at java.base/java.util.concurrent.CountedCompleter.tryComplete(CountedCompleter.java:592)
at java.base/java.util.stream.AbstractTask.compute(AbstractTask.java:328)
at java.base/java.util.concurrent.CountedCompleter.exec(CountedCompleter.java:746)
at java.base/java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:290)
at java.base/java.util.concurrent.ForkJoinPool$WorkQueue.topLevelExec(ForkJoinPool.java:1016)
at java.base/java.util.concurrent.ForkJoinPool.scan(ForkJoinPool.java:1665)
at java.base/java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1598)
at java.base/java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:183)

Does anyone have an idea what may cause this? It says something about permissions ... do I have to start it as admin?

Hello, same issue. It leads to this page for me:
https://forum.faforever.com/topic/607/faf-mod-vault-rules-regulations