Internal error. Database page XXXXXXXX had been changed during backup (page SCN=YYYYYYY, backup SCN=ZZZZZZZZ)

[Lucas Schatz]

Has anyone experienced this error while running nbackup? (In this case was nbackup running at level 4 )

• Internal error. Database page 5160318 had been changed during backup (page SCN=131336, backup SCN=131334)

Environment:

Firebird-3.0.4.33054-0.amd64

CentOS release 6.10 (Final)

Linux 2.6.32-754.23.1.el6.x86_64 #1 SMP Thu Sep 26 12:05:41 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux

Server Load during the episode: <1.00

Same error in another server (during nbackup level 5):

• Internal error. Database page 8067597 had been changed during backup (page SCN=67679, backup SCN=67677)

Environment:

Firebird-3.0.5.33220-0.amd64/

CentOS Linux release 8.2.2004 (Core)
Linux 4.18.0-193.19.1.el8_2.x86_64 #1 SMP Mon Sep 14 14:37:00 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux

Server Load during the episode: <1.15

No error log in firebird.log nor messages nor dmesg, APPARENTLY the database wasn't corrupted either

Note: I`m running nbackup 20 databases every minute during work time, for 1 year, and I got just 2 times this error so I`m assuming it`s a rare event, but I'm worried that this can corrupt the database at some level....

Note: I think that nbackup could eventually be running 2 instances at the same time, but normally one instance aborts because I always verify the existence of .delta file, or else nbackup would return this error:

• lost connection [ PROBLEM ON "begin backup". unsuccessful metadata update -ALTER DATABASE failed -Database is already in the physical backup mode SQLCODE:-607 ] 

Strangely I had already got this error 4 times this year:

• lost connection [ PROBLEM ON "end backup". unsuccessful metadata update -ALTER DATABASE failed -deadlock -update conflicts with concurrent update -concurrent transaction number is 434463421 SQLCODE:-607 ]

Thanks in advance