Donor services puts lots of time into gathering technical specs from donors who encounter errors, and the response rate to our requests for more information is low. If we asked for more details up front, we might have a better response rate from skipping the intermediate step.
If we could update the generic error message to both include the following message: "We're unable to process your transaction. For help, please contact donate@wikimedia.org. Please let us know which browser and donation link you are using, and provide a description or screenshot of the error." and to include a transaction ID from the payment processor, that would make investigating errors easier.