firebird-support - invalid request BLR at offset 27, on restore FB 3 database to 2.5

Subject	invalid request BLR at offset 27, on restore FB 3 database to 2.5
Author	Mr. John
Post date	2019-06-12T09:38:40Z

I'm trying to restore a FB 3 database to 2.5

Before fb3 backup,I copy from 2.5 gbak.exe to gbak2.exe into FB3 folder

then run

gbak2.exe -v -b "d:\db3.fdb" "d:\dbbk.gbk" -user SYSDBA -pass "mypass"

backup is done with no erorrs

I can restore it again to fb3 with no error but when I restore it to Fb2.5 I got this:

Starting restore. Current time: 12:25:06 PM

Invalid token.

invalid request BLR at offset 27.

BLR syntax error: expected valid BLR code at offset 28, encountered 210.

Exiting before completion due to errors.

Restore completed. Current time: 12:25:08 PM. Elapsed time: 00:00:01

restore is done from IBExpert

thanks