Is GPL-3.0-only compatible with LGPL-2.1?
It depends — here's on what:
LGPL and MPL-2.0 can feed a GPL work; EPL cannot. See overrides. Result license is the more restrictive of the inputs. You must satisfy every input license's notice and source-offer terms. Verify pairwise compatibility first.
Resulting work's license: GPL-3.0-only
General guidance, not legal advice.
Obligations when redistributing as open source
- GPL-3.0-only: retain the copyright notice and license text.
- GPL-3.0-only: state significant changes made to the code.
- GPL-3.0-only: provide complete corresponding source of the combined work.
- GPL-3.0-only: the combined distributed work must be licensed under GPL-3.0-only.
- LGPL-2.1: retain the copyright notice and license text.
- LGPL-2.1: state significant changes made to the code.
- LGPL-2.1: publish the source of any modifications to the library itself.
- LGPL-2.1: modifications to the library must remain under LGPL-2.1.
Other distribution models
The verdict is the same under every distribution model; the obligations differ. Check this pair in the tool to switch models.