[Dovecot] Problem when indexing maildir with a large number of folders

[Andre Rodier]

Hello everybody,

As part of a migration from exchange 2003 to dovecot, I have converted a lot of PST files for a user. I am importing his PST files in a maildir folder called
'Archives'. Actually, I reached about 770 'Archives' folders, and the total length of their names is about 59k characters. Thanks to wc!

I am using Maildir++

I can run the doveadm index command on the private namespace, however, I am not able to do this on the virtual folders.

Here the error I have:

> doveadm(john smith): Panic: file mail-index-transaction-update.c: line 875 (mail_index_update_header_ext): assertion failed: (offset <= (uint16_t)-1 && size
> <= (uint16_t)-1 && offset + size <= (uint16_t)-1)
> doveadm(gareth walters): Error: Raw backtrace: /usr/lib/dovecot/libdovecot.so.0(+0x4414a) [0x7f9b7100714a] ->
> /usr/lib/dovecot/libdovecot.so.0(default_fatal_handler+0x2a) [0x7f9b7100720a] -> /usr/lib/dovecot/libdovecot.so.0(i_fatal+0) [0x7f9b70fde82a] ->
> /usr/lib/dovecot/libdovecot-storage.so.0(+0xb8079) [0x7f9b7130a079] -> /usr/lib/dovecot/modules/lib20_virtual_plugin.so(virtual_storage_sync_init+0x788)
> [0x7f9b6f1775a8] -> /usr/lib/dovecot/libdovecot-storage.so.0(mailbox_sync_init+0x33) [0x7f9b712cf3e3] ->
> /usr/lib/dovecot/libdovecot-storage.so.0(mailbox_sync+0x27) [0x7f9b712cf507] -> doveadm(+0x16618) [0x7f9b719c8618] -> doveadm(+0x13346) [0x7f9b719c5346] ->
> doveadm(+0x13e21) [0x7f9b719c5e21] -> doveadm(doveadm_mail_try_run+0x161) [0x7f9b719c62e1] -> doveadm(main+0x3d1) [0x7f9b719c4ef1] ->
> /lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xfd) [0x7f9b70c57ead] -> doveadm(+0x13125) [0x7f9b719c5125]
> Aborted

I can see I have reached a limit, but is there any configuration value I can use to increase this limit, please?

Kind regards,
André.