This error may occur if, for example, extract destination has an invalid or missing URL.

If the error appears when you attempt to crop an image, the reason may be an error in the Variant activity. Such error can be also be not enough space on disk. As the Variant activity does not launch exceptions, but returns a XML with errors, the right way to identify such errors would be to add <Log> activity in the workflow; however, it may not work at all, as the workflow can break before the end, and the log will not be updated - as in case where the exception "The activity ‘cropForm’ has invalid parameter: Url" was a consequence of the failed creation of a variant, because of the full disk.

Note: the standard crop workflow won't create a variant if there's picture preview; however, custom workflows may be set to create variants in any case, and a full disk will break the operations. In code workflows, the Variant activity has the Mode property, that allows to create variant file without storing it in the database.

To correct this error

If the problem was a missing URL, correct the appropriate field in the extract destination.

If the problem was something else, check the disk space.