So. I've found the code on Github, and found references that say I need to run Dolphin 13.x - So, installed 13.1 now, and got the app up. Found that there were errors in the migration tool if running later than php 8.1 due to deprecated functions, so now running on 8.1

However, my dolphin site has a large number of users, 65188 in total. The spinning logo eventually stops, and if I reload the page, it shows status or Profiles as "Already started",but nothing proceeding or finishing. I left it overnight, and still the same status.

Any hints?

Self commenting on update progress, in case it helps anyone else.

I've increased max PHP time and maxed out memory allowed. Profiles migrated successfully. I then started on Paid Memberships levels, Members info... but ran into a problem.

Query:
INSERT INTO `sys_acl_levels` SET `Name` = ?, `Icon` = ?, `Description` = ?, `Active` = 'yes', `Order` = ?

It turns out I have a membership level that has a Name field that collides with an existing record in a default install and database table has a Unique constraint on the index for that field. For now, I changed the index to full text and it's imported OK. Just not sure how this will impact down the line yet.

Next problem / bug: My server is locked down for security. It passes the install checks in terms of disabled functions, but fwrite cannot be a disabled function. Upon checking, its required elsewhere inside Una as well, not just migration.

There are other issues about some deprecated functions that I think are related to data integrity in my forum (have not yet found root cause). To be continued.

Next problem: Data integrity in Dolphin. I found some forum topics with no posts. (Not sure why - but it was causing errors).

Pre-migration SQL to fix:

DELETE FROM bx_forum_topic
WHERE topic_id NOT IN (
    SELECT DISTINCT topic_id FROM bx_forum_post
);

Documenting earlier fix: My exisiting Dolphin site has a Premium membership level, and that caused issues migrating. So... the SQL below run against the Una database renamed the key for the built in premium level allowing mine to import.

UPDATE sys_acl_levels
	SET sys_acl_levels.Name = "_adm_prm_txt_level_unapremium"
	WHERE sys_acl_levels.name = "_adm_prm_txt_level_premium"
;

UPDATE sys_localization_keys
	SET sys_localization_keys.Key = "_adm_prm_txt_level_unapremium"
	WHERE sys_localization_keys.Key = "_adm_prm_txt_level_premium"
;

UPDATE sys_localization_strings
	SET sys_localization_strings.String = "UnaPremium"
	WHERE sys_localization_strings.String = "Premium"
;

Nice post to read. Helpful. I guess my biggest question is around support of the tool with various Una versions. Some of my research indicated that 13.x was the last supported version due to schema changes which did not play nice with the migration tool. To get me started, I am migrating with 13.1 right now - and it's generally working OK, with a few issues. (Conversations are being difficult right now). My plan was to do a two step - move to 13.1 and then to 14.x - but I'll keep working on it.

The other interesting thought from that thread - It seems to imply that migration to 14.x is possible directly, with the exception of the php version issue. In my case, I have the existing Dolphin site running on PHP 7.x, and the new Una running on 8.1 currently. I could go to later, but the migration script was throwing some deprecated warnings, so I settled on 8.1. If indeed it is possible to go direct to 8.4, I'd spend the time to find and fix the deprecated code in the migration tool, but would be curious if others could comment if it SHOULD work going direct to 14.x version of Una. If so, I'll take the time to try to get it in one step.

So. End result. I migrated to 13.1 - and then upgraded to 14.x. I covered most of my hacks above, but there may have been a few more. Losses: I lost about 60 forum threads and associated posts... but that was fairly small overall. It generally affected larger threads that spanned sub posts. Im sure lots of other things did not migrate cleanly, but nothing critical.