Upgrading 1.6.16 to 1.8.7 Failing with 500 Error

[BRickAstley]

Hello, 

I am working on a forum that is quite a bit out of date, so I'm making a large forum version jump upgrade. However, I haven't been able to get it off of the ground. 

I've been following the instructions posted here. When I go to /forums/install/upgrade.php, I select Previous Forum Version of 1.6.16 and hit next, and then get the following error after the webpage 'thinks' for about a minute: 

Internal Server Error
The server encountered an internal error or misconfiguration and was unable to complete your request.
Please contact the server administrator, [email protected] and inform them of the time the error occurred, and anything you might have done that may have caused the error.
More information about this error may be available in the server error log.
Additionally, a 500 Internal Server Error error was encountered while trying to use an ErrorDocument to handle the request.

I go to investigate my error.log and find this: 

[Tue Apr 12 18:21:07 2016] [error] [client 69.247.144.162] File does not exist: /home/brickastley/realmsbeyond.net/internal_error.html, referer: http://www.realmsbeyond.dreamhosters.com...pgrade.php

Things I have done to try and fix the problem so far:

1.  Deleted all forum files and database tables, and re-uploaded and tried again. 
   
2. Contacted webhosting support, who said: "Looking into this for you I was not able to find
   any indication as to what is causing the error within your Apache logs. I
   recommend going over the upgrade steps for your site once again."
   
3. Increase the PHP memory_limit to 128 and then 256 along with the max_execution_time to 1000 in PHP.ini. 
   

I'm really not sure what else to try here, please help! 

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Additional data: I've just now tried updating the forum incrementally; an upgrade from 1.6.16 to 1.6.18 works, but then upgrading from 1.6.18 to 1.8.0 results in the same error as above. So has an upgrade attempt from 1.6.16 to 1.8.4

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More investigation: I decided to go through the admin CP before running an upgrade, trying to disable/thin down anything I could to complete the upgrade. And when I attempted the Optimize Database action, the same 500 error came up. And I know my mybb_posts table is quite large...... Sure enough, trying to optimize *just* my mybb_posts table also gives the same error, and optimizing every other table at once works just fine. So that makes me think my issue is with something in the mybb_posts table now.

[.m.]

instead of live web server, can you try using local server (eg. XAMPP server) to do the upgrade ..

[BRickAstley]

I could do that, but I don't think that that's the problem anymore...

I just tried dropping all data from the mybb_posts table in my test environment, and the upgrade script instantly responded and did the upgrade successfully.

The size of that mybb_posts table is about 1GB. So do I just have too many forum posts to be able to update?

[Devilshakerz]

The size of that mybb_posts table is about 1GB. So do I just have too many forum posts to be able to update?

It might be too many to be done on your server - the 1.6→1.8 upgrade takes significantly longer than minor upgrades, mainly because users' IP addresses are being converted to a different format. The MyBB installation is most likely exceeding the time/resource limit.

You can try dropping data related to IP addresses in posts (make sure you have a backup):

UPDATE *posts SET `ipaddress`= ''

and trying the upgrade again;

nonetheless you might want to try the upgrade on your computer with disabled time and resource limits (it can take a while) and uploading the converted installation to your live server.

[BRickAstley]

That worked, thanks! Now to reconcile all the template changes....