'<attributename>' cannot be applied more than once to an assembly

The specified attribute can only be applied once to an attribute.

Error ID: BC31521

To correct this error

1. Remove redundant applications of this attribute.

2. If you are using a custom attribute you developed, modify AttributeUsageAttribute and set the AllowMultiple property to True.

See Also

Reference

AttributeUsageAttribute

AttributeUsageAttribute.AllowMultiple