debynory if it says "Oops", it means there's a more complete error message in the log file, or alternatively in the javascript console of the browser.
You may also enable debug in config.php so the error is printed on screen instead of "Oops".
I personally can't help with the import script, but I can help with a Flarum error if you share the error message 
clarkwinkelmann Thanks, I have this error in debug:
503 Service Unavailable
POST http://mysite.com/api/mybb-to-flarum
<!DOCTYPE html>
<html>
<head>
<title>503 Service Unavailable</title>
</head>
<body>
<h1>Error 503 Service Unavailable</h1>
<p>Service Unavailable</p>
<h3>Guru Meditation:</h3>
<p>XID: 20435029</p>
<hr>
<p>Varnish cache server</p>
</body>
</html>I think it's server 
Gatsu Without Varnish cache it's better (I immediately see the posts, without delay) but now I have this debug error:
POST http://mysite.com/api/mybb-to-flarum
{
"errors": [
{
"status": "500",
"code": "unknown",
"detail": "TypeError: Argument 1 passed to Flarum\\Discussion\\Discussion::setFirstPost() must be an instance of Flarum\\Post\\Post, null given, called in /home/omaggiec/public_html/vendor/michaelbelgium/mybb-to-flarum/src/Migrator.php on line 262 and defined in /home/omaggiec/public_html/vendor/flarum/core/src/Discussion/Discussion.php:201\nStack trace:\n#0 /home/omaggiec/public_html/vendor/michaelbelgium/mybb-to-flarum/src/Migrator.php(262): Flarum\\Discussion\\Discussion->setFirstPost(NULL)\n#1 /home/omaggiec/public_html/vendor/michaelbelgium/mybb-to-flarum/src/Controllers/MybbToFlarumController.php(68): Michaelbelgium\\Mybbtoflarum\\Migrator->migrateDiscussions(false, true, false, false)\n#2 /home/omaggiec/public_html/vendor/flarum/core/src/Http/RouteHandlerFactory.php(38): Michaelbelgium\\Mybbtoflarum\\Controllers\\MybbToFlarumController->handle(Object(Laminas\\Diactoros\\ServerRequest))\n#3 /home/omaggiec/public_html/vendor/flarum/core/src/Http/Middleware/DispatchRoute.php(65): Flarum\\Http\\RouteHandlerFactory->Flarum\\Http\\{closure}(Object(Laminas\\Diactoros\\ServerRequest), Array)\n#4 /home/omaggiec/public_html/vendor/laminas/laminas-stratigility/src/Next.php(61): Flarum\\Http\\Middleware\\DispatchRoute->process(Object(Laminas\\Diactoros\\ServerRequest), Object(Closure))\n#5 /home/omaggiec/public_html/vendor/flarum/core/src/Http/Middleware/SetLocale.php(50): Laminas\\Stratigility\\Next->handle(Object(Laminas\\Diactoros\\ServerRequest))\n#6 /home/omaggiec/public_html/vendor/laminas/laminas-stratigility/src/Next.php(61): Flarum\\Http\\Middleware\\SetLocale->process(Object(Laminas\\Diactoros\\ServerRequest), Object(Laminas\\Stratigility\\Next))\n#7 /home/omaggiec/public_html/vendor/flarum/core/src/Http/Middleware/CheckCsrfToken.php(45): Laminas\\Stratigility\\Next->handle(Object(Laminas\\Diactoros\\ServerRequest))\n#8 /home/omaggiec/public_html/vendor/laminas/laminas-stratigility/src/Next.php(61): Flarum\\Http\\Middleware\\CheckCsrfToken->process(Object(Laminas\\Diactoros\\ServerRequest), Object(Laminas\\Stratigility\\Next))\n#9 /home/omaggiec/public_html/vendor/flarum/core/src/Http/Middleware/AuthenticateWithHeader.php(55): Laminas\\Stratigility\\Next->handle(Object(Laminas\\Diactoros\\ServerRequest))\n#10 /home/omaggiec/public_html/vendor/laminas/laminas-stratigility/src/Next.php(61): Flarum\\Http\\Middleware\\AuthenticateWithHeader->process(Object(Laminas\\Diactoros\\ServerRequest), Object(Laminas\\Stratigility\\Next))\n#11 /home/omaggiec/public_html/vendor/flarum/core/src/Http/Middleware/AuthenticateWithSession.php(32): Laminas\\Stratigility\\Next->handle(Object(Laminas\\Diactoros\\ServerRequest))\n#12 /home/omaggiec/public_html/vendor/laminas/laminas-stratigility/src/Next.php(61): Flarum\\Http\\Middleware\\AuthenticateWithSession->process(Object(Laminas\\Diactoros\\ServerRequest), Object(Laminas\\Stratigility\\Next))\n#13 /home/omaggiec/public_html/vendor/flarum/core/src/Http/Middleware/RememberFromCookie.php(51): Laminas\\Stratigility\\Next->handle(Object(Laminas\\Diactoros\\ServerRequest))\n#14 /home/omaggiec/public_html/vendor/laminas/laminas-stratigility/src/Next.php(61): Flarum\\Http\\Middleware\\RememberFromCookie->process(Object(Laminas\\Diactoros\\ServerRequest), Object(Laminas\\Stratigility\\Next))\n#15 /home/omaggiec/public_html/vendor/flarum/core/src/Http/Middleware/StartSession.php(61): Laminas\\Stratigility\\Next->handle(Object(Laminas\\Diactoros\\ServerRequest))\n#16 /home/omaggiec/public_html/vendor/laminas/laminas-stratigility/src/Next.php(61): Flarum\\Http\\Middleware\\StartSession->process(Object(Laminas\\Diactoros\\ServerRequest), Object(Laminas\\Stratigility\\Next))\n#17 /home/omaggiec/public_html/vendor/flarum/core/src/Api/Middleware/FakeHttpMethods.php(29): Laminas\\Stratigility\\Next->handle(Object(Laminas\\Diactoros\\ServerRequest))\n#18 /home/omaggiec/public_html/vendor/laminas/laminas-stratigility/src/Next.php(61): Flarum\\Api\\Middleware\\FakeHttpMethods->process(Object(Laminas\\Diactoros\\ServerRequest), Object(Laminas\\Stratigility\\Next))\n#19 /home/omaggiec/public_html/vendor/flarum/core/src/Http/Middleware/ParseJsonBody.php(28): Laminas\\Stratigility\\Next->handle(Object(Laminas\\Diactoros\\ServerRequest))\n#20 /home/omaggiec/public_html/vendor/laminas/laminas-stratigility/src/Next.php(61): Flarum\\Http\\Middleware\\ParseJsonBody->process(Object(Laminas\\Diactoros\\ServerRequest), Object(Laminas\\Stratigility\\Next))\n#21 /home/omaggiec/public_html/vendor/flarum/core/src/Http/Middleware/HandleErrors.php(57): Laminas\\Stratigility\\Next->handle(Object(Laminas\\Diactoros\\ServerRequest))\n#22 /home/omaggiec/public_html/vendor/laminas/laminas-stratigility/src/Next.php(61): Flarum\\Http\\Middleware\\HandleErrors->process(Object(Laminas\\Diactoros\\ServerRequest), Object(Laminas\\Stratigility\\Next))\n#23 /home/omaggiec/public_html/vendor/laminas/laminas-stratigility/src/MiddlewarePipe.php(84): Laminas\\Stratigility\\Next->handle(Object(Laminas\\Diactoros\\ServerRequest))\n#24 /home/omaggiec/public_html/vendor/middlewares/request-handler/src/RequestHandler.php(84): Laminas\\Stratigility\\MiddlewarePipe->process(Object(Laminas\\Diactoros\\ServerRequest), Object(Laminas\\Stratigility\\Next))\n#25 /home/omaggiec/public_html/vendor/laminas/laminas-stratigility/src/Next.php(61): Middlewares\\RequestHandler->process(Object(Laminas\\Diactoros\\ServerRequest), Object(Laminas\\Stratigility\\Next))\n#26 /home/omaggiec/public_html/vendor/middlewares/base-path-router/src/BasePathRouter.php(97): Laminas\\Stratigility\\Next->handle(Object(Laminas\\Diactoros\\ServerRequest))\n#27 /home/omaggiec/public_html/vendor/laminas/laminas-stratigility/src/Next.php(61): Middlewares\\BasePathRouter->process(Object(Laminas\\Diactoros\\ServerRequest), Object(Laminas\\Stratigility\\Next))\n#28 /home/omaggiec/public_html/vendor/laminas/laminas-stratigility/src/Middleware/OriginalMessages.php(42): Laminas\\Stratigility\\Next->handle(Object(Laminas\\Diactoros\\ServerRequest))\n#29 /home/omaggiec/public_html/vendor/laminas/laminas-stratigility/src/Next.php(61): Laminas\\Stratigility\\Middleware\\OriginalMessages->process(Object(Laminas\\Diactoros\\ServerRequest), Object(Laminas\\Stratigility\\Next))\n#30 /home/omaggiec/public_html/vendor/middlewares/base-path/src/BasePath.php(53): Laminas\\Stratigility\\Next->handle(Object(Laminas\\Diactoros\\ServerRequest))\n#31 /home/omaggiec/public_html/vendor/laminas/laminas-stratigility/src/Next.php(61): Middlewares\\BasePath->process(Object(Laminas\\Diactoros\\ServerRequest), Object(Laminas\\Stratigility\\Next))\n#32 /home/omaggiec/public_html/vendor/laminas/laminas-stratigility/src/MiddlewarePipe.php(84): Laminas\\Stratigility\\Next->handle(Object(Laminas\\Diactoros\\ServerRequest))\n#33 /home/omaggiec/public_html/vendor/laminas/laminas-stratigility/src/MiddlewarePipe.php(73): Laminas\\Stratigility\\MiddlewarePipe->process(Object(Laminas\\Diactoros\\ServerRequest), Object(Laminas\\Stratigility\\EmptyPipelineHandler))\n#34 /home/omaggiec/public_html/vendor/laminas/laminas-httphandlerrunner/src/RequestHandlerRunner.php(96): Laminas\\Stratigility\\MiddlewarePipe->handle(Object(Laminas\\Diactoros\\ServerRequest))\n#35 /home/omaggiec/public_html/vendor/flarum/core/src/Http/Server.php(42): Laminas\\HttpHandlerRunner\\RequestHandlerRunner->run()\n#36 /home/omaggiec/public_html/index.php(26): Flarum\\Http\\Server->listen()\n#37 {main}"
}
]
}And stuck always on 1K discussions and 40K posts
EDIT: Resolved!!! (For now)
I had 0 on firstpost column in mybb database, about a discussion. Deleted discussion and now it's importing again 
mybb_threads table -> check firstpost column, you don't have to have 0
But again stuck This time I have this error:
POST http://mysite.com/api/mybb-to-flarum
{
"errors": [
{
"status": "405",
"code": "method_not_allowed",
"detail": "Flarum\\Http\\Exception\\MethodNotAllowedException: GET in /home/omaggiec/public_html/vendor/flarum/core/src/Http/Middleware/DispatchRoute.php:60\nStack trace:\n#0 /home/omaggiec/public_html/vendor/laminas/laminas-stratigility/src/Next.php(61): Flarum\\Http\\Middleware\\DispatchRoute->process(Object(Laminas\\Diactoros\\ServerRequest), Object(Laminas\\Stratigility\\Next))\n#1 /home/omaggiec/public_html/vendor/flarum/core/src/Http/Middleware/SetLocale.php(50): Laminas\\Stratigility\\Next->handle(Object(Laminas\\Diactoros\\ServerRequest))\n#2 /home/omaggiec/public_html/vendor/laminas/laminas-stratigility/src/Next.php(61): Flarum\\Http\\Middleware\\SetLocale->process(Object(Laminas\\Diactoros\\ServerRequest), Object(Laminas\\Stratigility\\Next))\n#3 /home/omaggiec/public_html/vendor/flarum/core/src/Http/Middleware/CheckCsrfToken.php(37): Laminas\\Stratigility\\Next->handle(Object(Laminas\\Diactoros\\ServerRequest))\n#4 /home/omaggiec/public_html/vendor/laminas/laminas-stratigility/src/Next.php(61): Flarum\\Http\\Middleware\\CheckCsrfToken->process(Object(Laminas\\Diactoros\\ServerRequest), Object(Laminas\\Stratigility\\Next))\n#5 /home/omaggiec/public_html/vendor/flarum/core/src/Http/Middleware/AuthenticateWithHeader.php(55): Laminas\\Stratigility\\Next->handle(Object(Laminas\\Diactoros\\ServerRequest))\n#6 /home/omaggiec/public_html/vendor/laminas/laminas-stratigility/src/Next.php(61): Flarum\\Http\\Middleware\\AuthenticateWithHeader->process(Object(Laminas\\Diactoros\\ServerRequest), Object(Laminas\\Stratigility\\Next))\n#7 /home/omaggiec/public_html/vendor/flarum/core/src/Http/Middleware/AuthenticateWithSession.php(32): Laminas\\Stratigility\\Next->handle(Object(Laminas\\Diactoros\\ServerRequest))\n#8 /home/omaggiec/public_html/vendor/laminas/laminas-stratigility/src/Next.php(61): Flarum\\Http\\Middleware\\AuthenticateWithSession->process(Object(Laminas\\Diactoros\\ServerRequest), Object(Laminas\\Stratigility\\Next))\n#9 /home/omaggiec/public_html/vendor/flarum/core/src/Http/Middleware/RememberFromCookie.php(51): Laminas\\Stratigility\\Next->handle(Object(Laminas\\Diactoros\\ServerRequest))\n#10 /home/omaggiec/public_html/vendor/laminas/laminas-stratigility/src/Next.php(61): Flarum\\Http\\Middleware\\RememberFromCookie->process(Object(Laminas\\Diactoros\\ServerRequest), Object(Laminas\\Stratigility\\Next))\n#11 /home/omaggiec/public_html/vendor/flarum/core/src/Http/Middleware/StartSession.php(61): Laminas\\Stratigility\\Next->handle(Object(Laminas\\Diactoros\\ServerRequest))\n#12 /home/omaggiec/public_html/vendor/laminas/laminas-stratigility/src/Next.php(61): Flarum\\Http\\Middleware\\StartSession->process(Object(Laminas\\Diactoros\\ServerRequest), Object(Laminas\\Stratigility\\Next))\n#13 /home/omaggiec/public_html/vendor/flarum/core/src/Api/Middleware/FakeHttpMethods.php(29): Laminas\\Stratigility\\Next->handle(Object(Laminas\\Diactoros\\ServerRequest))\n#14 /home/omaggiec/public_html/vendor/laminas/laminas-stratigility/src/Next.php(61): Flarum\\Api\\Middleware\\FakeHttpMethods->process(Object(Laminas\\Diactoros\\ServerRequest), Object(Laminas\\Stratigility\\Next))\n#15 /home/omaggiec/public_html/vendor/flarum/core/src/Http/Middleware/ParseJsonBody.php(28): Laminas\\Stratigility\\Next->handle(Object(Laminas\\Diactoros\\ServerRequest))\n#16 /home/omaggiec/public_html/vendor/laminas/laminas-stratigility/src/Next.php(61): Flarum\\Http\\Middleware\\ParseJsonBody->process(Object(Laminas\\Diactoros\\ServerRequest), Object(Laminas\\Stratigility\\Next))\n#17 /home/omaggiec/public_html/vendor/flarum/core/src/Http/Middleware/HandleErrors.php(57): Laminas\\Stratigility\\Next->handle(Object(Laminas\\Diactoros\\ServerRequest))\n#18 /home/omaggiec/public_html/vendor/laminas/laminas-stratigility/src/Next.php(61): Flarum\\Http\\Middleware\\HandleErrors->process(Object(Laminas\\Diactoros\\ServerRequest), Object(Laminas\\Stratigility\\Next))\n#19 /home/omaggiec/public_html/vendor/laminas/laminas-stratigility/src/MiddlewarePipe.php(84): Laminas\\Stratigility\\Next->handle(Object(Laminas\\Diactoros\\ServerRequest))\n#20 /home/omaggiec/public_html/vendor/middlewares/request-handler/src/RequestHandler.php(84): Laminas\\Stratigility\\MiddlewarePipe->process(Object(Laminas\\Diactoros\\ServerRequest), Object(Laminas\\Stratigility\\Next))\n#21 /home/omaggiec/public_html/vendor/laminas/laminas-stratigility/src/Next.php(61): Middlewares\\RequestHandler->process(Object(Laminas\\Diactoros\\ServerRequest), Object(Laminas\\Stratigility\\Next))\n#22 /home/omaggiec/public_html/vendor/middlewares/base-path-router/src/BasePathRouter.php(97): Laminas\\Stratigility\\Next->handle(Object(Laminas\\Diactoros\\ServerRequest))\n#23 /home/omaggiec/public_html/vendor/laminas/laminas-stratigility/src/Next.php(61): Middlewares\\BasePathRouter->process(Object(Laminas\\Diactoros\\ServerRequest), Object(Laminas\\Stratigility\\Next))\n#24 /home/omaggiec/public_html/vendor/laminas/laminas-stratigility/src/Middleware/OriginalMessages.php(42): Laminas\\Stratigility\\Next->handle(Object(Laminas\\Diactoros\\ServerRequest))\n#25 /home/omaggiec/public_html/vendor/laminas/laminas-stratigility/src/Next.php(61): Laminas\\Stratigility\\Middleware\\OriginalMessages->process(Object(Laminas\\Diactoros\\ServerRequest), Object(Laminas\\Stratigility\\Next))\n#26 /home/omaggiec/public_html/vendor/middlewares/base-path/src/BasePath.php(53): Laminas\\Stratigility\\Next->handle(Object(Laminas\\Diactoros\\ServerRequest))\n#27 /home/omaggiec/public_html/vendor/laminas/laminas-stratigility/src/Next.php(61): Middlewares\\BasePath->process(Object(Laminas\\Diactoros\\ServerRequest), Object(Laminas\\Stratigility\\Next))\n#28 /home/omaggiec/public_html/vendor/laminas/laminas-stratigility/src/MiddlewarePipe.php(84): Laminas\\Stratigility\\Next->handle(Object(Laminas\\Diactoros\\ServerRequest))\n#29 /home/omaggiec/public_html/vendor/laminas/laminas-stratigility/src/MiddlewarePipe.php(73): Laminas\\Stratigility\\MiddlewarePipe->process(Object(Laminas\\Diactoros\\ServerRequest), Object(Laminas\\Stratigility\\EmptyPipelineHandler))\n#30 /home/omaggiec/public_html/vendor/laminas/laminas-httphandlerrunner/src/RequestHandlerRunner.php(96): Laminas\\Stratigility\\MiddlewarePipe->handle(Object(Laminas\\Diactoros\\ServerRequest))\n#31 /home/omaggiec/public_html/vendor/flarum/core/src/Http/Server.php(42): Laminas\\HttpHandlerRunner\\RequestHandlerRunner->run()\n#32 /home/omaggiec/public_html/index.php(26): Flarum\\Http\\Server->listen()\n#33 {main}"
}
]
}Now stuck on 3K discussions and 63K posts.
OTHER EDIT: Maybe now it works, I don't know why.
Only I noticed that even if the red error message comes out, in the administration panel the posts and discussions continued to increase, up to almost everyone, only a few it did not import but patience, most yes.
Then I had to put some things in place, for example when I clicked on the homepage (logo of the forum) it always gave me POST null error, so I pressed on "mark all posts as read" and now it seems to be fine too.
I actived together the options "migrate categories, posts and threads" because otherwise it did not correlate with each other forum and post and it was a disaster. Now, however, it seems that the categories are also more or less ok.
I am migrating from Mybb to flarum and during half migration, I get the error:
production.ERROR: TypeError: Argument 1 passed to Flarum\Discussion\Discussion::setFirstPost() must be an instance of Flarum\Post\Post, null given, called in /usr/home/username/domains/mydomain.pro/flarum/vendor/michaelbelgium/mybb-to-flarum/src/Migrator.php on line 262 and defined in /usr/home/username/domains/mydomain.pro/flarum/vendor/flarum/core/src/Discussion/Discussion.php:201
Stack trace:
:
Please help
turtles Must be a data problem. A discussion always has a first post (the first post = the discussion). Same with mybb, the thread = the first post. So I have no idea why your mybb forum doesn't have that
EDIT: nvm, the thread/post might be soft-deleted. If u don't specify they can be migrated then it can indeed show that error. I could reproduce the error by creating a mybb thread and a reply on that thread, soft deleting both the reply and thread and then saying i want to migrate soft deleted threads.
EDIT:
debynory turtles The setFirstPost exception is fixed in v5.1
There might be confusion about these 2 options for migrating soft-deleted posts/threads as a thread is actually a post. So maybe i'll simplify it to 1 option
MichaelBelgium Hello, commenting on the lines in which I received the error helped me. The migration was successful 
Good job!
Hi! I'm the guy that has been posting issues and PRs in github just passing by.
I have a big mybb forum (40k users, 2k active lurkers/day, 900k posts) I'm looking forward to migrate into Flarum (well, at least evaluate it as an option).
so expect me to be asking questions here and there
thanks for your great work!
Hi, will this extension work on the latest MyBB 1.8 ? Thanks.
Hey, thanks for creating this extension. I used it on one of my forums a few weeks ago and it worked perfectly.
But I'm trying to move another MyBB forum to Flarum and your extension isn't working. It says
Oops! Something went wrong. Please reload the page and try again.
I checked the log folder /storage/logs and it's empty. JavaScript console shows:
request.js:173 POST https://forums.MYSITE.com/api/mybb-to-flarum 500
(anonymous) @ request.js:173
(anonymous) @ request.js:23
(anonymous) @ request.js:22
e.request @ Application.js:352
(anonymous) @ MybbToFlarumPage.js:166
Promise.then (async)
o.onsubmit @ MybbToFlarumPage.js:165
I.handleEvent @ render.js:888
admin#/mybb-to-flarum:1 Uncaught (in promise) i {status: 500, options: {…}, xhr: XMLHttpRequest, responseText: null, response: null, …}
Promise.then (async)
(anonymous) @ MybbToFlarumPage.js:178
Promise.then (async)
o.onsubmit @ MybbToFlarumPage.js:165
I.handleEvent @ render.js:888
I narrowed it down to the migrate users option being the cause of the error. Unchecking migrate avatars has no effect.
These work either individually or altogether:
I checked the usernames and saw that one of them was using an email address as a username so I renamed them and tried again. Same error.
I checked to see what kind of restrictions Flarum puts on usernames by registering a new account and found out that dots and spaces are not allowed.
The username may only contain letters, numbers, and dashes.
Using MySQL, I update the database of mybb_users and replaced all usernames containing spaces and dots to dashes.
Same error.
I deleted most of the user base and attempted to migrate it. Same error, but this time it did import some users. Again, no error log.
Deleting every user except my admin user also did not work, same error. MyBB doesn't seem to let me delete my own admin account.
Any help would be appreciated.
Neuro The JS error doesn't say much, it'd be more helpful if u enable debug of your flarum instance. Then you get a log file in the myflarum/storage/logs folder. Then I could help more i bet!
Neuro I checked the log folder /storage/logs and it's empty. JavaScript console shows:
Very odd... Error logs should be added there regardless of debug mode.
That being said, if you do enable debug mode and try sending the request, there'll be a "debug" button on the error message, which if you click, you should see more info about what's going wrong.
Okay, I enabled debug mode and it's the same thing, the debug button shows no error:
500
POST https://forums.MYSITE.com/api/mybb-to-flarum
null
Nothing in storage/logs either.
Any ideas?
Should I start my own thread about this issue? I'm still trying to migrate from MyBB to Flarum.
Neuro since it seems to be an issue with this extension I think the discussion can continue here.
Neuro Nothing in storage/logs either.
Check the browser network tab while performing the request. null in the error modal can indicate the response wasn't valid JSON and failed parsing. The network tab will show the full actual response, which might include a PHP notice or warning in HTML format.
Nothing shows up in the response tab:
This request has no response data available
I modified the import script and made it assign the imported users' username and email to a counter variable and "test", so
Username: Test1
Email: Test1@test.com
Username: Test2
Email: Test2@test.com
Even set the password to "test" just in case.
It's the same error,
It imports some users and then stops randomly. The number of users it imports seems to vary for some reason, like 400 +/- 5.
Don't know what else to do.
Is there no way to diagnose this problem? I tried modifying the script to log every user imported to the console but it doesn't seem to be working.
Neuro by any chance, have you been able to narrow it down to some form of representative dataset? Something that might suggest what portion of the data is causing the issue?
If not I'll try and take a look at the code in a bit more detail tomorrow.
askvortsov Well, it's not
Not sure what else could be at fault here. I don't know how to find out either.
A 500 can be generated either by Flarum, PHP or the webserver. Inspect the response headers of the request to see which one is to blame. Then look at server logs to find an error.
And in case you have a config.php make sure to enable debug by changing it to true instead of false.
