Bug ID 1959549: Upgrade to 17.5.0 or later overwrites #TMSH-VERSION in bigip_base.conf when source UCS is pre-17.5.0

Last Modified: Jan 19, 2026

Affected Product(s):
BIG-IP Install/Upgrade(all modules)

Known Affected Versions:
17.5.0, 17.5.1, 17.5.1.2, 17.5.1.3, 21.0.0

Opened: May 26, 2025

Severity: 2-Critical

Symptoms

When upgrading from versions below 17.5.0 to 17.5.0 or later, the #TMSH-VERSION marker in bigip_base.conf is rewritten to the target system version instead of preserving the source UCS version. This prevents MCPD schema migration code from executing, potentially causing configuration mismatches and missing schema-based workarounds.

Impact

Overwriting TMSH-VERSION in bigip_base.conf file, uses the wrong schema when loading the configuration and miss applying MCP schema based workarounds.

Conditions

- roll-forward upgrade from v14.x/v15.x/v16.x/v17.1.x to v17.5.1 and later releases. upgrade from v17.5.x to v21.x and later versions is not affected.

Workaround

None

Fix Information

None

Behavior Change

Guides & references

K10134038: F5 Bug Tracker Filter Names and Tips