Python pip install fails with conflicting dependencies

pip install fails with ResolutionImpossible or ERROR: Cannot install X and Y because they have conflicting dependencies. The dependency resolver cannot find a combination that satisfies all requirements.

(1) Use pip install --dry-run to see what would be installed without changing anything. (2) Check which packages conflict: pip check. (3) Pin specific versions that are known compatible in requirements.txt. (4) Use pip-compile (pip-tools) to resolve dependencies offline and generate a locked requirements.txt. (5) Try upgrading all conflicting packages: pip install --upgrade package1 package2. (6) Use a virtual environment — never install into system Python. (7) For ML projects with complex deps: use conda which handles binary dependencies better.

pip's dependency resolver (since pip 20.3) is strict — it won't install packages with conflicting version requirements. Older pip would silently install incompatible versions, causing runtime errors.