there are some errors while i run dbexport to backup:

tail online.log
17:35:39 Assert Failed: rowalter: PTOCOPYVC: collen (0xb3) > max_vc_len (0xb) (cmpoff: 0x286, uncmpoff 0x6fb

17:35:39 Informix Dynamic Server 2000 Version 9.21.UC2
17:35:39 Who: Session(48, szccbusr@szccbdb, 1771, 357133428)
Thread(77, sqlexec, 154689a8, 1)
File: rssupp.c Line: 2658
17:35:39 Results: altering older version row to latest version failed
17:35:39 stack trace for pid 1138 written to /home/tmp/af.435846a
17:35:39 See Also: /home/tmp/af.435846a, shmem.435846a.0
17:35:55 Assert Failed: read_record: decompress_row, source = 13790a65, target = 15c3d534
17:35:55 Informix Dynamic Server 2000 Version 9.21.UC2
17:36:10 Who: Session(48, szccbusr@szccbdb, 1771, 357133428)
Thread(77, sqlexec, 154689a8, 1)
File: rsread.c Line: 2517
17:36:10 Results: Record not read
17:36:10 Action: Please notify Informix Technical Support.
17:36:10 stack trace for pid 1138 written to /home/tmp/af.435846a
17:36:10 See Also: /home/tmp/af.435846a, shmem.435846a.1
17:36:19 read_record: invalid rowid = 717101, partnum = 500091
17:37:18 Booting Language <spl> from module <>
17:37:18 Loading Module <SPLNULL>
17:37:19 Checkpoint Completed: duration was 0 seconds.
17:37:19 Checkpoint loguniq 38, logpos 0x1afc018

17:37:20 'szccb_cm' - New logging mode: NO LOGGING
17:38:47 Assert Failed: rowalter: PTOCOPYVC: collen (0xb3) > max_vc_len (0xb) (cmpoff: 0x286, uncmpoff 0x6fb

17:38:47 Informix Dynamic Server 2000 Version 9.21.UC2
17:38:47 Who: Session(51, szccbusr@szccbdb, 2140, 357133880)
Thread(80, sqlexec, 15469588, 1)
File: rssupp.c Line: 2658
17:38:47 Results: altering older version row to latest version failed
17:38:47 stack trace for pid 1138 written to /home/tmp/af.4388526
17:38:47 See Also: /home/tmp/af.4388526, shmem.4388526.0
17:38:50 Assert Failed: read_record: decompress_row, source = 15c99265, target = 15c8a38c
17:38:50 Informix Dynamic Server 2000 Version 9.21.UC2
17:38:50 Who: Session(51, szccbusr@szccbdb, 2140, 357133880)
Thread(80, sqlexec, 15469588, 1)
File: rsread.c Line: 2517
17:38:50 Results: Record not read
17:38:50 Action: Please notify Informix Technical Support.
17:38:50 stack trace for pid 1138 written to /home/tmp/af.4388526
17:38:50 See Also: /home/tmp/af.4388526, shmem.4388526.1
17:39:10 read_record: invalid rowid = 717101, partnum = 500091
17:42:23 Fuzzy Checkpoint Completed: duration was 0 seconds, 1 buffers not flushed.
17:42:23 Checkpoint loguniq 38, logpos 0x1afe0a4

attchment is the af.4388526

Thanks for your help!

Bug: 153841 FAST RECOVERY RESTORES INPLACE ALTERED PAGES WITH WRONG ALTER VERSION
Date: 2001-11-14 Category: ONLINE
Type: SW Submitter: michaelm
Component: RSAM RSAM MISCELLANEOUS

Description:
The problem shows up on tables that were inplace altered.

This happens if we reuse an empty page that had had old version rows on it
to insert new rows of an altered version.

"oncheck -cD d:t" will find this error:

ERROR:Count of version 0 data pages 1 != pnv_pages 0

"oncheck -pp d:t 0x101" will show the page version as next = 0 instead
of 1000000.

Fixed in 9.21.UC7

Thanks for ur help.
But i dont know how to resolve it. Where can i find the patch? Our informmix version is 9.21.UC2.

You must call your local technical support number.
A patch is made i think, or you can upgrade to version 9.21.UC7

how about this bug?
Bug: 119881 ASSERT FAILED: READ_RECORD: DECOMPRESS_ROW, SOURCE = A086018,
TARGET = A3294A4 WHEN USING DIRTY READ ISOLATION
fixed in version 7.31.UD1 and above

or this one

bug: 128228 ASSERT FAILED: READ_RECORD: DECOMPRESS_ROW WHILE RUNNING FRAG01
TEST
AGAINST 9.21.UN205
Date: 2000-04-18 Category: ONLINE Type:

Description:
The test frag01 (/vobs/qa_tristar/kcqa/kernel/frag01) was run.
got an Af during function read_record()