Builds Getting Stuck at a Certain Point

Symptoms

The progress bar stops at X% for a long time. The status is still Building. The page does not update.

Debugging

1. Check the build log

In SL Migrations → Packages, click the package that is building → watch the live log. The last line tells you which phase the plugin is stuck in:

DATABASE - dumping SQL
ARCHIVE - compressing files
STORAGE - uploading to the cloud

2. Check the database

A long-running MySQL query may be holding a lock. If you have access to the server, check the MySQL process list - if you see a query stuck for over 60s on the site's database → it may be the build dumping.

Common causes

ARCHIVE phase stuck

A file that is too large: a single file > 1GB (an old database dump, heavy media) → slow to compress
Slow disk: I/O bottleneck
Memory leak: the PHP process eats RAM → the OS swaps → extremely slow

Fix:

Exclude large files from the backup
Switch to the DupArchive engine (chunked, does not load everything into RAM)
Raise memory_limit to 1-2 GB

DATABASE phase stuck

Table lock: MySQL locks a table → the dump cannot get the data
Large transaction: a running query holds a row lock

Fix:

Wait for the other query to finish and build again
Build during off-peak hours (3-5 AM)
In Settings → Package → Database, change the dump mode if needed

STORAGE phase stuck

Upload to cloud storage is slow or times out
Network drop

Fix:

Test the connection to the storage on the Tools page
Temporarily back up locally only and upload manually later
Raise the cURL timeout in php.ini

Force restart a build

If a build has been stuck for over 30 minutes with no progress:

SL Migrations → Packages → click Cancel on that package
Wait 1-2 minutes for the plugin to process the cancellation
If it still does not finish, you can delete the lock file slm_pro_lock.bin in the plugin folder (through FTP/SFTP)
Create a new backup

Builds Getting Stuck at a Certain Point