Collection was modified; enumeration operation may not execute

[kiranbhadani]

We are getting this error frequently in production environment, not able to find the cause of the issue

System.InvalidOperationException: Collection was modified; enumeration operation may not execute. at System.Collections.Generic.HashSet`1.Enumerator.MoveNext() at WebOptimizer.Asset.ExpandGlobs(IAsset asset, IWebHostEnvironment env) at WebOptimizer.Asset.GenerateCacheKey(HttpContext context)