In unity Editor:

401 Unauthorized

Check security plugins. In my case, I couldn’t get the token because of WP Security Hardening.

After getting the token… 403 Forbidden

Once Exported to WebGL:

Running it in an Apache Server (compression error)

It is required to add a .htaccess file in the running folder with the following code

# This configuration file should be uploaded to the server as "<Application Folder>/Build/.htaccess"
# This configuration has been tested with Unity 2020.1 builds, hosted on Apache/2.4
# NOTE: "mod_mime" Apache module must be enabled for this configuration to work.
<IfModule mod_mime.c>
# The following lines are required for builds without decompression fallback, compressed with gzip
RemoveType .gz
AddEncoding gzip .gz
AddType application/octet-stream .data.gz
AddType application/wasm .wasm.gz
AddType application/javascript .js.gz
AddType application/octet-stream .symbols.json.gz
# The following lines are required for builds without decompression fallback, compressed with Brotli
RemoveType .br
RemoveLanguage .br
AddEncoding br .br
AddType application/octet-stream .data.br
AddType application/wasm .wasm.br
AddType application/javascript .js.br
AddType application/octet-stream .symbols.json.br
# The following line improves loading performance for uncompressed builds
AddType application/wasm .wasm
# Uncomment the following line to improve loading performance for gzip-compressed builds with decompression fallback
# AddEncoding gzip .unityweb
# Uncomment the following line to improve loading performance for brotli-compressed builds with decompression fallback
# AddEncoding br .unityweb

Memory Out Bounds (Browser)

Just changing the !@#$ API compatibility level to .NET 2.0 (Other Settings / Configuration / …)

Error Serializing Jsons

JsonSerializationException: Unable to find a constructor to use for type JWT_wp. A class should either have a default constructor, one constructor with arguments or a constructor marked with the JsonConstructor attribute. Path 'token', line 1, position 9.
at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.CreateNewObject (Newtonsoft.Json.JsonReader reader, Newtonsoft.Json.Serialization.JsonObjectContract objectContract, Newtonsoft.Json.Serialization.JsonProperty containerMember,

I included the class, however I set up the unity optimization configuration to “Managed Stripping Level” to HIGH. That means the class was not included in the compilation. Either should be included in the link.xml or lowering the Managed Stripping Level