Bug 5526409- FAL gaps reported at standby for log not yet written at primary
This is a known Bug 5526409 which is fixed in 10.2.0.4 and 11.1.
To solve the issue, please upgrade to the newest patchset since Bug 5526409 is fixed in 10.2.0.4.
Their is no impact of these messages on the database. You can safely ignore these messages.
Furthermore there are One-off Patch for Bug 5526409 on top of 10.2.0.3 available for some platforms. Please check Patches & Updates within My Oracle Support MOS.
BUG:5526409- FAL[CLIENT]: FAILED TO REQUEST GAP SEQUENCE BUT NO GAPS FOUNDITPUB
PATCH:5526409- FAL[CLIENT]: FAILED TO REQUEST GAP SEQUENCE BUT NO GAPS FOUNDITPUB