This rule is applied when you enter data into the field.
When you are asking a reader for their email address, you can use a simple » address validation function to make sure the address has a valid structure. Each option in a drop-down box is indexed in the array Annoyingly, there is no simple way to check which radio button out of a group is selected — you have to check through each element, linked with Boolean AND operators .cookie, but the error would rear its ugly head the minute I touched my assemblies.The long term solution was to add a machine Key element to my Web.config file – asking visitors to delete a specific cookies when visiting my site was not a viable option. Http Exception: Validation of viewstate MAC failed.How I fixed the Validation of viewstate MAC failed. If this application is hosted by a Web Farm or cluster, ensure that configuration specifies the same validation Key and validation algorithm. If this application is hosted by a Web Farm or cluster, ensure that configuration specifies the same validation Key and validation algorithm.