pypa/pip · error · InstallationError

Editable requirements are not allowed as constraints

Error message

Editable requirements are not allowed as constraints

What it means

InstallationError from check_invalid_constraint_type when a constraint entry is editable ('-e ./pkg' or '-e git+...'). Editable installs cannot act as constraints because a constraint only narrows version selection for a named project; an editable is an install instruction. The resolver rejects it (with a preceding deprecation notice) rather than silently misinterpreting it.

Source

Thrown at src/pip/_internal/resolution/resolvelib/factory.py:553

            else:
                # require the base from the link
                yield self.make_requirement_from_candidate(cand)
                if ireq.extras:
                    # require the extras on top of the base candidate
                    yield self.make_requirement_from_candidate(
                        self._make_extras_candidate(cand, frozenset(ireq.extras))
                    )

    def collect_root_requirements(
        self, root_ireqs: list[InstallRequirement]
    ) -> CollectedRootRequirements:
        collected = CollectedRootRequirements([], {}, {})
        for i, ireq in enumerate(root_ireqs):
            if ireq.constraint:
                # Ensure we only accept valid constraints
                problem = check_invalid_constraint_type(ireq)
                if problem:
                    raise InstallationError(problem)
                if not ireq.match_markers():
                    continue
                assert ireq.name, "Constraint must be named"
                name = canonicalize_name(ireq.name)
                if name in collected.constraints:
                    collected.constraints[name] &= ireq
                else:
                    collected.constraints[name] = Constraint.from_ireq(ireq)
            else:
                reqs = list(
                    self._make_requirements_from_install_req(
                        ireq,
                        requested_extras=(),
                    )
                )
                if not reqs:
                    continue
                template = reqs[0]

View on GitHub (pinned to d7d0d0a394)

Solutions

Remove '-e' from any line in the constraints file.
Move editable installs into the regular requirements file ('-r'), not the constraints file ('-c').
If you need to pin a local editable, pin the underlying project name+version in the constraint and keep '-e' on the install side.
Re-run pip after editing to confirm.

Example fix

# before — constraints.txt
-e ./local/mylib

# after — move to requirements.txt
-e ./local/mylib
# and in constraints.txt keep only:
mylib==1.0

Defensive patterns

Strategy: validation

Validate before calling

def constraints_have_no_editable(path: str) -> bool:
    bad = [l.strip() for l in open(path) if l.strip().startswith('-e ')]
    if bad:
        print(f'editable in constraints: {bad}'); return False
    return True

Type guard

def is_non_editable_constraint(line: str) -> bool:
    return not line.strip().startswith('-e ')

Try / catch

if not constraints_have_no_editable('constraints.txt'):
    print('move -e lines out of constraints file')
else:
    run_pip(['install', '-c', 'constraints.txt', 'pkg'])

Prevention

Never put '-e' lines in a constraints file.
Separate install requirements (-r) from constraints (-c) physically.
Lint for '-e' in constraints in CI.

When it happens

Trigger: A file passed with '-c' contains a line like '-e ./local/pkg' or '-e git+https://.../pkg.git'. collect_root_requirements calls check_invalid_constraint_type, req.editable is True, and the problem string is raised.

Common situations: Reusing a monorepo dev-requirements file as both install and constraints; copy-pasting an editable line into a constraints file by mistake; teams merging a constraints file and a dev-install file.

Related errors

AI-assisted analysis of pypa/pip@d7d0d0a394 (2026-08-04). Data as JSON: /data/errors/4d9c74eb03576191.json. Report an issue: GitHub.