Customers could run into the same error easily. There is always a customer who reports it first. The solution made, could be made available for all other customers to down load it as well, also for those who are using newer versions.

Pro-active working can be done two ways. One way is to adjust all outstanding versions. Another way is to adjust the version of the customer and higher versions. The latter is economically more interesting. Provide a scheme to Support and Maintenance so it becomes clear which versions will be maintained an which will not. Of course you have to inform your customers upfront about this maintenance policy.

Higher Service Level

When you have several versions of a product pro-active maintenance could help you improve your service level.

An error found in version B, could also occur in version A (pre-decessor of version B) or C (successor of version B). When solving the error in the two other versions as well without a customer complaining about is, is pro-active maintenance.

As soon as a customer logs the issue on one of the two other versions you have the solution immediately available. Via the Self-Service functions the customer could easily find the solution himself without disturbing Support.

You have to decide if your approach will be re-active or pro-active. Re-active is cheaper for the short term but in the long term Pro-active maintenance is cheaper and increases your service level.