LFX and Langflow version compatibility
Langflow and LFX are versioned together on the same major.minor line, so you can always tell which LFX release runs which flows.
Compatibility contract
LFX X.Y.N is guaranteed compatible with any flow exported from Langflow X.Y.M.
The major and minor numbers must match.
The patches .N for LFX and .M for Langflow are released independently. An LFX patch fix does not require a Langflow patch release, and vice versa.
When LFX and a flow share the same major version but differ on minor, such as a flow exported from Langflow 1.9.x run with LFX 1.10.x, individual components may have been updated since the flow was saved.
Use lfx upgrade to check compatibility and apply safe automatic fixes before running or serving such a flow.
For more information, see Check and upgrade flows with lfx upgrade.
Compatibility matrix
| Langflow version | Compatible LFX version | Notes |
|---|---|---|
| 1.10.x | 1.10.x | Fully compatible. Same major.minor line. |
| 1.11.x | 1.11.x | Fully compatible. Same major.minor line. |
| 1.9.x or earlier | 1.10.x | Use lfx upgrade --upgrade-flow=safe to apply safe component schema upgrades before running. |
| Any 1.x.x | 0.5.x | LFX 0.5.x was a standalone release before version alignment. It is no longer compatible with Langflow 1.10+ flows. |
Check and upgrade flows with lfx upgrade
The lfx upgrade command inspects a flow against the built-in component registry and reports any components that have become incompatible or that have safe automatic upgrades available.
lfx upgrade compares each component in the flow against a bundled index at _assets/component_index.json that ships with the LFX release.
Run it with no flags to get a read-only compatibility report. The command reads your flow JSON, walks through every component node, and prints one line per node with its status. It does not modify the file.
_10lfx upgrade my-flow.json
Example output:
_10 [SAFE] Agent (AgentComponent) - id: abc123_10 [OK] Chat Output (ChatOutput) - id: def456
| CLI output | What it means | Example |
|---|---|---|
[OK] | Component matches the current registry. | No action needed. |
[SAFE] | Component code changed, but ports and fields your flow uses still line up. lfx upgrade --write can apply this update automatically. | An output that previously emitted only Message now also supports Data. |
[BREAKING] | A port or field your flow relies on was removed. | An input that accepted Message and Data now accepts only Message and your flow uses a Data component. |
[BLOCKED] | The component type no longer exists in this LFX build. | A bundle-only component is not installed in your environment. |
To apply fixes or enforce stricter checks, run:
_10# Apply all safe upgrades and overwrite the file_10lfx upgrade my-flow.json --write_10_10# Fail if any safe upgrades are still pending (use after a dry run before running `--write`)_10lfx upgrade my-flow.json --strict
Inline compatibility checking with --upgrade-flow
Both lfx run and lfx serve accept an --upgrade-flow option so you can apply compatibility checks at execution without a separate lfx upgrade step.
_10# Check only — fail if any component is blocked_10lfx run my-flow.json --upgrade-flow=check "Hello world"_10_10# Apply safe upgrades in memory, then run_10lfx run my-flow.json --upgrade-flow=safe "Hello world"_10_10# Same options for serve_10lfx serve my-flow.json --upgrade-flow=safe
| Mode | Behavior |
|---|---|
check | Reports compatibility issues and exits non-zero if any component is blocked. No changes are written to disk. |
safe | Applies all safe upgrades in memory, then runs or serves the flow. Blocked components still cause a non-zero exit. |
Pin versions
Pin lfx~=1.10.0 in requirements.txt to track all patch releases for a given Langflow minor without crossing into the next minor automatically.
_10# requirements.txt — allows 1.10.1, 1.10.2, … but not 1.11.0_10lfx~=1.10.0
Migrating from LFX 0.5.x to 1.10.0
LFX was realigned from its standalone 0.5.x line onto Langflow's major.minor line, so the version number jumps from 0.5.0 to 1.10.0 in one release. This is a version-numbering change, not 95 minor releases of new features.
This jump can affect existing dependency pins in unexpected ways:
| Pin style | Effect |
|---|---|
lfx==0.5.x or lfx<1.0 | Does not upgrade. The deployment stays on 0.5.x. |
lfx>=0.5,<1 | Does not upgrade. The upper bound excludes 1.10.0. |
lfx>=0.5 (no upper bound) | Upgrades automatically to 1.10.0 on the next install. |
Going forward, pin with lfx~=1.10.0 so you receive compatible patches without silently crossing minor lines.
