Why is my site displaying a “503 Service Temporarily Unavailable” error?

This is most likely caused by your site having met its maximum concurrent connection limit. Shared hosting accounts are subject to the following limits:

Linux
– Linux Economy – 50 Concurrent Connections
– Linux Deluxe – 100 Concurrent Connections
– Linux Unlimited – 200 Concurrent Connections

Windows
– Windows Economy – 50 Concurrent Connections
– Windows Deluxe – 100 Concurrent Connections
– Windows Unlimited – 150 Concurrent Connections

MySQL connection limits from your hosting server to the MySQL server follow the same limitations as Linux Shared Hosting.

MSSQL connections are limited to 100 concurrent connections.

Larger files also cause connections to remain open longer, while your site’s visitors download them. Smaller files/text lead to shorter connections. As an example, a blog with fewer readers might perform fine with an economy account and its 50 concurrent connections. However, a blog with streaming media or a higher patronage would probably need more connections.

To resolve these issues, consider upgrading to a plan with a higher concurrent connection limit.