We are in a state where some Salesforce instances are on the Summer 15 pre-release, and others on the current Generally Available (GA) release of Spring 15.
Orgs on Summer 15 will be either:
- Orgs provisioned through the Summer 15 pre-release signup page.
- Sandbox orgs that wen through the early upgrade option.
The former will all be using the
gs0.salesforce.com domain. The latter will be on whatever
CS instance they were provisioned on.
When you build something in the Summer 15 timeframe (API version 34), your package will use that API version.
If you need to test package install, the easiest way to do this is to provision another pre-release org and attempt the install there.
If you want to get the feature you created into a specific org that is not yet on the new release, there are two possibilities.
- If you have used features specific to the new release, you must wait until the GA date.
- If you have not used an pre-release features, you can install using one of the many deployment tools by connecting to your pre-release org using the currently GA version and deploying to the other org.