i. 500 Internal Server Error
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500 Internal Server Error is an indication that your website is hit by memory limit configured in the server. Try refreshing the page after one minute.

ii. 503 Error
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If your website hits "maximum number of concurrent connections allowed", your website will show this error. Try refreshing the page after one minute.

iii. 508 Resource Limit Is Reached
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This error is an indication that website is continuously hitting the resources limits in the server. Reason for this error may be CPU usage, RAM usage and/or number of concurrent connections. If you see this error, you can login to cpanel & find out the resource limit hit by your website  by navigating to Analysis & Log Files > Resoucre Usage Overview.


What can I do if my website is hitting limits?
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A resource usage spike once in a while is something you can ignore and it should not cause any major issue to your website. If the issue appears to be frequent, you should consider optimising the code of your website or upgrading to a more powerful plan.