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Tldr
MySql started crashing on startup. Given the error message the datatable is likely corrupted, see the log below. How can I reset/purge that.
I use Nextcloud only locally as a data storage with 2 users. So completely nuking the database is an option as long as my files stick around.
Running sudo nextcloud.export or sudo nextcloud.occ maintenance:mode --on doesn’t work because of mysql not starting.
The error message gives me this link https://dev.mysql.com/doc/refman/8.0/en/forcing-innodb-recovery.html however that is scary and I am not quite sure how to do that in snap.
2 questions.
- What data does the database contain
- Can I just snap uninstall nextcloud and start from scratch while maintaining my data
The Basics
- Nextcloud Server version (e.g., 29.x.x):
- 23.0.12snap1, I know that is old. But it kept running so there was no reason to change it.
- Operating system and version (e.g., Ubuntu 24.04):
Linux Mint 19.1
- When did this problem seem to first start?
I moved the server to a new router, so I changed the target IP address on my client. Started failing right away.
- Installation method (e.g. AlO, NCP, Bare Metal/Archive, etc.)
snap
- Are you using CloudfIare, mod_security, or similar? (Yes / No)
no, local only
Summary of the issue you are facing:
See the Logs, MySql crashes.
Log entries
MySql
2025-11-02T14:33:02.639380Z 0 [System] [MY-010931] [Server] /snap/nextcloud/33289/bin/mysqld: ready for connections. Version: '8.0.31' socket: '/tmp/sockets/mysql.sock' port: 0 Source distribution.
2025-11-02T14:33:03.123893Z 0 [ERROR] [MY-013183] [InnoDB] Assertion failure: btr0cur.cc:285:btr_page_get_prev(get_block->frame, mtr) == page_get_page_no(page) thread 140298646705920
InnoDB: We intentionally generate a memory trap.
InnoDB: Submit a detailed bug report to http://bugs.mysql.com.
InnoDB: If you get repeated assertion failures or crashes, even
InnoDB: immediately after the mysqld startup, there may be
InnoDB: corruption in the InnoDB tablespace. Please refer to
InnoDB: http://dev.mysql.com/doc/refman/8.0/en/forcing-innodb-recovery.html
InnoDB: about forcing recovery.
2025-11-02T14:33:03Z UTC - mysqld got signal 6 ;
Most likely, you have hit a bug, but this error can also be caused by malfunctioning hardware.
BuildID[sha1]=ec0f4cec275638b03b6929605fe1030d0e582494
Thread pointer: 0x7f99ac000b20
Attempting backtrace. You can use the following information to find out
where mysqld died. If you see no messages after this, something went
terribly wrong...
stack_bottom = 7f99d2ffca80 thread_stack 0x100000
/snap/nextcloud/33289/bin/mysqld(my_print_stacktrace(unsigned char const*, unsigned long)+0x3d) [0x5592507b068d]
/snap/nextcloud/33289/bin/mysqld(print_fatal_signal(int)+0x3c3) [0x55924f7094d3]
/snap/nextcloud/33289/bin/mysqld(my_server_abort()+0x6e) [0x55924f7095ee]
/snap/nextcloud/33289/bin/mysqld(my_abort()+0xa) [0x5592507aa17a]
/snap/nextcloud/33289/bin/mysqld(ut_dbg_assertion_failed(char const*, char const*, unsigned long)+0x2e9) [0x559250adcbd9]
/snap/nextcloud/33289/bin/mysqld(btr_cur_latch_leaves(buf_block_t*, page_id_t const&, page_size_t const&, unsigned long, btr_cur_t*, mtr_t*)+0x71f) [0x559250b2293f]
/snap/nextcloud/33289/bin/mysqld(btr_cur_search_to_nth_level(dict_index_t*, unsigned long, dtuple_t const*, page_cur_mode_t, unsigned long, btr_cur_t*, unsigned long, char const*, unsigned long, mtr_t*)+0x18e5) [0x559250b2d4e5]
/snap/nextcloud/33289/bin/mysqld(row_search_index_entry(dict_index_t*, dtuple_t const*, unsigned long, btr_pcur_t*, mtr_t*)+0x146) [0x559250a3b4f6]
/snap/nextcloud/33289/bin/mysqld(+0x24b47e2) [0x559250a327e2]
/snap/nextcloud/33289/bin/mysqld(+0x24b5fd6) [0x559250a33fd6]
/snap/nextcloud/33289/bin/mysqld(row_purge_step(que_thr_t*)+0xf73) [0x559250a35b03]
/snap/nextcloud/33289/bin/mysqld(que_run_threads(que_thr_t*)+0xf50) [0x5592509e79d0]
/snap/nextcloud/33289/bin/mysqld(trx_purge(unsigned long, unsigned long, bool)+0x197) [0x559250a9c7b7]
/snap/nextcloud/33289/bin/mysqld(srv_purge_coordinator_thread()+0x13e2) [0x559250a6f602]
/snap/nextcloud/33289/bin/mysqld(std::thread::_State_impl<std::thread::_Invoker<std::tuple<Detached_thread, void (*)()> > >::_M_run()+0xc4) [0x55925097a834]
/usr/lib/x86_64-linux-gnu/libstdc++.so.6(+0xbd6df) [0x7f9a334476df]
/lib/x86_64-linux-gnu/libpthread.so.0(+0x76db) [0x7f9a3391e6db]
/lib/x86_64-linux-gnu/libc.so.6(clone+0x3f) [0x7f9a32b0474f]
Trying to get some variables.
Some pointers may be invalid and cause the dump to abort.
Query (0): is an invalid pointer
Connection ID (thread ID): 0
Status: NOT_KILLED
Nextcloud
Please provide the log entries from your Nextcloud log that are generated during the time of problem (via the Copy raw option from Administration settings->Logging screen or from your nextcloud.log located in your data directory). Feel free to use a pastebin/gist service if necessary.
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