This is really annoying. We encountered the same issue with EPiServer.CMS.TinyMce v4.2.0 in combination with ImageVault.EPiServer.UI v12.19.7. Breaking changes must be handled more gracefully.
The breaking change has been confirmed and bug issued as CMS-27603. However, there is currently no information available regarding when or how this issue will be resolved.
Optimizely has updated the AddSettings method on TinyMceSettings
Now the plugin that is delivered with TinyMce 4.1 fails... in service registration, but it shouldnt should it?
System.MissingMethodException: Method not found: 'EPiServer.Cms.TinyMce.Core.TinyMceSettings EPiServer.Cms.TinyMce.Core.TinyMceSettings.AddSetting(System.String, System.Object)'.
at Epicweb.Optimizely.Plugin.ServiceCollectionExtension.<>c__DisplayClass0_0.<AddFrontifyPlugin>b__1(TinyMceConfiguration config)
We can see when refactoring that Opti has added a optional param in 4.2
TinyMceSettings AddSetting(string key, object value, bool registerAsEditorOption = true)
TinyMceSettings AddSetting(string key, object value)
How to solve this without updating the plugin package and releasing a new package in feed? Is this a breaking change? Pretty annoying, if so