如果使用Carthage，请确保使用copy-frameworks脚本，而不是使用Embed & Sign作为嵌入内容。我得到了同样的错误，因为我忘记了。

可能的原因是

framework which you are using may not be built for simulator architecture(x86_64), you can check the compatibility by going to framework folder (framework_name.framework --> modules --->framework_name.swiiftModule-->) in this path you should see arm/i386/x86_64 support files if you have updated to new Xcode, the frameworks you are using are not compatible to the newer compiler version, so vendor needs to share the recent compatible one, in this case you will not be able to run on both device and simulator

No doubt that the fix in case of Xcode 12.3 is to setup the Validate Workspace property in the target's build setting. However if you check the diff after this change, the reason of the build error is the missing parameter (VALIDATE_WORKSPACE) from the project file, not the value of the parameter. So you don't need the value to be YES. You need to add the value to the project settings and you can leave it on the default value (NO). At the first time, it shows up in the Build Settings with NO, but only because that is the default value of the missing parameter.

TLDR; 在不更改项目设置的情况下，转到目标的构建设置，找到“验证工作区”，将其设置为YES，然后设置回NO。

我想你所链接的框架只是为arm架构而构建的。你不能在模拟器中运行它。您将需要框架的作者来构建一个“通用框架”。

如果使用Carthage，请确保使用copy-frameworks脚本，而不是使用Embed & Sign作为嵌入内容。我得到了同样的错误，因为我忘记了。

我在Xcode v12.3和Universal(fat) Framework(.framework)上运行了这个错误

Building for iOS Simulator, but the linked and embedded framework was built for iOS + iOS Simulator.

解决方案1:是Toggle/Toggle验证工作区(不是默认)

方案二:使用XCFramework[About]