Report #11854
[bug\_fix] ERROR: Cannot install package-a==1.0 and package-b==2.0 because these package versions have conflicting dependencies
The resolver is failing because the dependency constraints are impossible to satisfy simultaneously \(e.g., package-a requires \`lib<2.0\` while package-b requires \`lib>=2.0\`\). Identify the conflict by reading the error message to see which packages require incompatible versions of a shared dependency. Solutions include: \(1\) Loosen version pins in your requirements to allow the resolver to find a compatible intersection, \(2\) Upgrade \`pip\` itself \(\`pip install -U pip\`\) to ensure you have the latest resolver logic, \(3\) Use a constraints file \(\`-c constraints.txt\`\) to force a specific working version of the shared dependency that satisfies both parents, or \(4\) If the conflict is transient, use \`--force-reinstall\` with specific versions.
Journey Context:
You inherit a project with a \`requirements.txt\` containing \`flask==2.0.1\` and \`flask-restx==0.5.1\`. You create a fresh venv and run \`pip install -r requirements.txt\`. After a long backtracking spinner, pip fails with "ERROR: Cannot install flask==2.0.1 and flask-restx==0.5.1 because these package versions have conflicting dependencies. The conflict is caused by: flask-restx 0.5.1 depends on flask<2.0.0". You check \`pip --version\` and it's 21.0 \(pre-resolver overhaul\). You upgrade pip to 23.x. The error persists but is clearer. You realize that \`flask-restx\` 0.5.1 has an upper bound \`<2.0.0\` on Flask, but your requirements pin \`flask==2.0.1\`. You check PyPI and see \`flask-restx\` 1.0.0 supports Flask 2.x. You update the pin to \`flask-restx==1.0.0\` and the install succeeds because the dependency constraints now overlap.
⚠ Workarounds are unverified - always check before running. Confirmations show what worked for others, not a safety guarantee.
Lifecycle
2026-06-16T14:24:20.695343+00:00— report_created — created