InvalidOperationException

I have the following stack trace:

System.InvalidOperationException: This access control list is not in canonical form and therefore cannot be modified.
at System.Security.AccessControl.CommonAcl.ThrowIfNotCanonical()
at System.Security.AccessControl.CommonAcl.AddQualifiedAce(SecurityIdentifier sid, AceQualifier qualifier, Int32 accessMask, AceFlags flags, ObjectAceFlags objectFlags, Guid objectType, Guid inheritedObjectType)
at System.Security.AccessControl.DiscretionaryAcl.AddAccess(AccessControlType accessType, SecurityIdentifier sid, Int32 accessMask, InheritanceFlags inheritanceFlags, PropagationFlags propagationFlags)
at System.Security.AccessControl.CommonObjectSecurity.ModifyAccess(AccessControlModification modification, AccessRule rule, Boolean& modified)
at System.Security.AccessControl.CommonObjectSecurity.AddAccessRule(AccessRule rule)
at System.Security.AccessControl.FileSystemSecurity.AddAccessRule(FileSystemAccessRule rule)

What is the reason I see this exception?

---
#### Document Details

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* ID: a7c391b9-99c2-c104-e419-2e2f520acf61
* Version Independent ID: 5d777a33-c027-ede6-cf0b-70f989e22113
* Content: [FileSystemSecurity.AddAccessRule(FileSystemAccessRule) Method (System.Security.AccessControl)](https://docs.microsoft.com/en-us/dotnet/api/system.security.accesscontrol.filesystemsecurity.addaccessrule?f1url=https%3A%2F%2Fmsdn.microsoft.com%2Fquery%2Fdev15.query%3FappId%3DDev15IDEF1%26l%3DEN-US%26k%3Dk(System.Security.AccessControl.FileSystemSecurity.AddAccessRule)%3Bk(TargetFrameworkMoniker-.NETFramework%2CVersion%3Dv2.0)%3Bk(DevLang-csharp)%26rd%3Dtrue&view=netframework-4.7.2#applies-to)
* Content Source: [xml/System.Security.AccessControl/FileSystemSecurity.xml](https://github.com/dotnet/dotnet-api-docs/blob/master/xml/System.Security.AccessControl/FileSystemSecurity.xml)
* Product: **dotnet-api**
* GitHub Login: @dotnet-bot
* Microsoft Alias: **dotnetcontent**