Import Troubleshooting
Specific forum imports
Make sure you also check each forum importers codex page for specific issues relating to each forum, the list can be found here.
The import gets ‘stuck’
When importing topics or replies the import may become ‘stuck’ and the import will no longer continue importing.
These types of faults are typically due to some encoding issue in that post. Sometimes this is from an encoding conversion to UTF8 that was done at some point. Whatever it is, it’s nearly impossible to detect without setting a time limit on queries and bisecting the difference until we can narrow down the offending entry, and skip it. Because queries could naturally take a long time, and because it results in missed data, I’m not comfortable with this approach.
The workaround is to find and delete the offending topic or reply which is time consuming and tricky but the only way at this stage.
Here’s how I do debug this and find the offending topics/replies:
- Once the import hangs, click
stop, take a note of where it was up to, e.g. Converting 11,299 – 11,300 - Click
startagain and the import will continue from where it left off - If it hangs again, take note of where it was up to again
- Once finished make a fresh copy of the source database
- Now drop all the rows in the database that are not in the range of rows that failed during import
- Perform a fresh import using this database with the “Rows Limit” setting set to `1`
- The import should hang on the offending topic/reply
- Again, take note of the topic/reply it was up to
- Click stop, click start again to continue on
- Once you have your list of offenders and the import has finished delete these rows from the database and test again to make sure it completes without hanging
- Now back in your full database (presumably a copy of the original) delete these same rows from the database and run the import again
Tweaking MySQL
When you have very large forums to import it can take quite a long time.
@ezyridah performed a MyBB import of 1 million+ messages, close to 40k topics and a 400+ members and took ~48 hours, he has added some custom PHP & MySQL tweaks that helped speed things up a bit, you can see what settings he used here, and beware, this is pretty advanced and not for the faint hearted.
Cyrillic Usernames
If you need to import users ‘Cyrillic’ before importing install and activate @SergeyBiryukov‘s Allow Cyrillic Usernames.
