Getting ERR_TOO_MANY_REDIRECTS with Lightsail Wordpress Multisite Path based

The ERR_TOO_MANY_REDIRECTS error you're experiencing with your WordPress Multisite installation is a configuration issue related to redirect loops in your setup.

This error occurs when your WordPress instance is continuously redirecting between HTTP and HTTPS, or between different URL formats, without ever resolving to a final destination. The error log shows that requests are exceeding the limit of 10 internal redirects, which confirms this issue.

There are several potential causes for this problem:

1. Redirect Configuration: Your WordPress might be trying to redirect from HTTP to HTTPS, but not checking if the connection is already on HTTPS, causing an infinite redirect loop.

2. Cloudflare Integration: Since you're using Cloudflare as a CDN and DNS provider, there might be conflicts between Cloudflare's SSL settings and your WordPress configuration.

3. Multisite Path Configuration: The specific issue with the admin URL for your subsite suggests there might be a problem with how WordPress Multisite is handling path-based sites.

To resolve this issue, try the following steps:

1. Check your WordPress configuration for redirect settings, particularly in your wp-config.php file or through any security plugins that might be enforcing HTTPS.

2. Verify your Cloudflare SSL/TLS settings to ensure they're properly configured for your domain.

3. Review your .htaccess file for any conflicting redirect rules.

4. If you're using the Bitnami WordPress stack, you might need to run the configure_app_domain script for both your main domain and the path-based subdomain structure.

5. Temporarily disable Cloudflare (set to DNS only mode) to determine if the issue is related to Cloudflare's proxy settings.

For WordPress Multisite specifically, ensure that your network settings are correctly configured for path-based sites and that your permalink structure is compatible with your multisite setup.
Sources
This page isn’t working - ERR_TOO_MANY_REDIRECTS | AWS re:Post
Server Not Found (DNS_PROBE_FINISHED_NXDOMAIN) on Lightsail WordPress MultiSite after attaching Static IP and domain with configure_app_domain | AWS re:Post