## List<T>.ForEach can throw exception when modifying list item

### Scope
Edge

### Version Introduced
4.5

### Source Analyzer Status
Available

### Change Description
Beginning in .NET 4.5, a `List<T>.ForEach` enumerator will throw an InvalidOperationException exception if an element in the calling collection is modified. Previously, this would not throw an exception but could lead to race conditions.

- [x] Quirked
- [ ] Build-time break

### Recommended Action
Ideally, code should be fixed to not modify lists while enumerating their elements because that is never a safe operation. To revert to the previous behavior, though, an app may target .NET 4.0.

### Affected APIs
* ``M:System.Collections.Generic.List`1.ForEach(System.Action{`0})``

### Category
Core

[More information](https://msdn.microsoft.com/en-us/library/hh367887\(v=vs.110\).aspx#core)

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