There is a problem with STS 3.5.0
https://issuetracker.springsource.com/browse/STS-3792
org.codehaus.groovy.eclipse 2.9.0.xx-201403261719-e43j8 is unknown in the solver!
These are the steps I took to fix it and it allowed me to use eclipse marketplace
Help -> Check for updates
Problem Occured
"JDT Core patch with Java 8 Support for Groovy-Eclipse plugin" is not applicable to the current configuration and will not be installed.
An internal error occurred during: "Searching alternate solutions...".
org.codehaus.groovy.eclipse 2.9.0.xx-201403261719-e43j8 is unknown in the solver!
If you get this error, then these are the steps to fix it:
Help
About Spring Tool Suite
Installation Details
Eclipse Java Development Tools Patch with Java 8 support (for Kepler SR2)
Uninstall...
restart
Then to verify that the error is gone:
Help -> Check for updates
No updates were found.
It should be ok now. But you need to install the Java 8 support
Then follow these steps:
Help
Install new software...
Work with: SpringSource Update Site for Eclipse 4.3 - http://download.springsource.com/release/TOOLS/update/e4.3
[x] Groovy-Eclipse
Next
Next
I accept
Finish
Restart
That should do it.
I had the same problem. Check if groovy-eclipse is installed. If it is not, then you need to install it first then install STS.
Check this website for installation https://www.function1.com/2016/06/installing-eclipse-groovy-plugin
