Confuser 1.4.1 with .NET 4.7.2 Winforms exe
Create a project with only the default rename mode (unicode) and renPdb=true:
<protection id="rename"> <argument name="mode" value="unicode" /> <argument name="renPdb" value="true" /> </protection>

Run it and get:
[DEBUG] Renaming... [ERROR] Unknown error occurred. Exception: System.NullReferenceException: Object reference not set to an instance of an object. at Confuser.Renamer.RenamePhase.Execute(ConfuserContext context, ProtectionParameters parameters) at Confuser.Core.ProtectionPipeline.ExecuteStage(PipelineStage stage, Action1 func, Func1 targets, ConfuserContext context) at Confuser.Core.ConfuserEngine.RunPipeline(ProtectionPipeline pipeline, ConfuserContext context) at Confuser.Core.ConfuserEngine.RunInternal(ConfuserParameters parameters, CancellationToken token) Failed at 1:27 PM, 0:00 elapsed.