Fixing Import Install upload failures

Import Install cannot upload / launch

Symptoms

Dragging and dropping the archive onto the import page → the spinner never finishes
The upload fails with a 413 Request Entity Too Large error
The upload finishes but clicking Continue does nothing

Causes + fixes

1. PHP upload limits

PHP has these limits:

upload_max_filesize - maximum file size
post_max_size - maximum POST request size
memory_limit - RAM per request

Fix: raise these values. How you do it depends on the hosting:

Shared hosting: use cPanel → MultiPHP INI Editor, or add a .user.ini in the web root
VPS: edit the PHP-FPM php.ini and reload
Managed hosting: contact support

Reference values:

upload_max_filesize = 2G
post_max_size = 2G
memory_limit = 1024M
max_execution_time = 600

2. Web server limits (Nginx/Apache)

Nginx has a default client_max_body_size of 1 MB. Apache has LimitRequestBody.

Fix: contact your hosting provider to raise this limit, or change it yourself if you have access.

3. Upload through FTP/SFTP instead of the web

For a large archive (>1GB), uploading through the web is not practical. Upload through FTP/SFTP into the wp-content/backups-slm/import/ folder, then go to SL Migrations → Import → From Server and pick the uploaded file.

4. Browser tab closed / network drop

The upload was cancelled midway. The plugin leaves a temporary file behind.

Fix: delete the temporary file in the backups-slm/import/ folder and upload again.

5. Permissions on the `import/` folder

The folder is not writable → the upload fails.

Fix: set 755 on the folder, with the web server user as owner.

Errors after the upload finishes

If the upload finishes but clicking Continue gives no response:

Open DevTools (F12) → Console and look for JS errors
Network tab → look at the AJAX response from admin-ajax.php
Check the web server's error log
Raise max_execution_time (a large import needs >300s)