Check for updates fails

[mattcoz]

An error occurred while collecting items to be installed
session context was:(profile=SDKProfile, phase=org.eclipse.equinox.internal.p2.engine.phases.Collect, operand=, action=).
No repository found containing: osgi.bundle,net.jeeeyul.eclipse.themes,2.3.1.I20180720-143135
No repository found containing: osgi.bundle,net.jeeeyul.eclipse.themes.ui,2.3.1.I20180720-143135
No repository found containing: org.eclipse.update.feature,net.jeeeyul.eclipse.themes.feature,2.3.1.I20180720-143135