I am working on an existing integration . I created an email campaign through CC UI . While debugging my project i got the error "Error 400: This campaign is of type TEMPLATE_V2, which is not accessible using the v1 API; the v2 API is required." when campaign details was sought to ConstantContact API . As I remeber the same was working fine previously . Has any change happened recently in API ? Also is there any other way to create email campaign through UI so that existing code can fetch created campaign details ?
The reason that you are seeing this for the first time is because the type "TEMPLATE_V2" is only associated with campaigns created by our new third-generation editor. Due to the age of the V1 API, there are some major incompatibilities in how the two systems see campaigns that ultimately resulted in the decision to take this approach.
If you are working with a new account when testing your integration, that is likely the reason that you are seeing this, as most new accounts now come with our third-generation editor enabled. In terms of working around this, you would either need to create custom code campaigns (which do not currently use the new editor), or use a different account that has not yet been upgraded to the new editor.
Another option would be to investigate what is required to update your integration to use our V2 API. If you have an interest in this, we do have a number of SDKs that can help to speed up development. Those SDKs can be found here: http://developer.constantcontact.com/libraries/libraries.html
If you have any questions for me, please reply and I will be happy to help!