WordPress menus are lost on server migration!

I had this issue for a very long time: a live server with a bunch of menus was allright. Trying to migrate the DB locally (for syncing), usually ended up in a mess, because menus were gone. No matter what tools I was usings, be it mysqldump, migrate db or anything else, menus were GONE! 

Worst part? This only happened only on some sites. On the bright side, I didn’t needed to make this sync too often so wasn’t that bad to do it manually, so I didn’t worry too much. 

Because I didn’t find any patterns, I assumed that is somehow related to a path conversion (given that I’m using a Windows machine).

I was wrong. Partially. Not really. But ignorance is bliss, right?

So fast forward few years. Today. I have this client with a huge site. HUGE. There are a bunch of menus. A lot of specific page menus. There are about 30 to 40 menus. Syncing those manually? Totally not an option! 

I started to dig into WP table structure. Dumping databases in various stages, then diff the whole db see what changes (as a side note, this approach looks pretty intriguing!).

So I managed to pinpoint the place where the menu locations are kept:

INSERT INTO `wp_options` VALUES (143,'theme_mods_MY_THEME_NAME','a:7:{i:0;b:0;s:18:\"nav_menu_locations\";a:4:{s|...

My very first though was: „wait a minute, I’m sure that serialization is messed up!”. Checking then double checking the serialized string and, sure enough, the serialization was correct. 

But then few lines above in the sql dump, I’ve noticed this:

INSERT INTO `wp_options` VALUES (110,'theme_mods_twentyseventeen','a:2

Yes! You see, the menus are stored as theme_mods and the theme is identified by… folder name!

And while on the remote server the theme folder was named MY_THEME_NAME, locally was… MY_THEME_NAME.org

Sure enough, If I ever used other theme modifications (custom styling, custom logo, widgets and so on), the pattern would had been more obvious.

TL;DR: use the same theme folder name on all servers.