If you are trying to validate a file and it gets stuck at 45%, this is usually down to an issue in the source file you are importing that no longer matches the file format that has been setup in ePay.
It is important to make sure nothing has changed in the way you generate the file. To ensure the format is correct you will need to open the input file and compare this to the file format used in ePay. Please see related article: How do I compare the file format ePay is using against the input file?
If you have checked the file and you are happy it is correct, but are still getting the validation stuck at 45%, please check that the account running ePay has permissions to create an in progress folder. See article: Unable to Validate - Error: unable to copy to working folder.