I have a form with a dynamic number of fields. Submitting it worked fine until I tried out a very large version of it. The development log was not very helpful:
Invalid or incomplete POST params
As it turned out, the following exception did not reach the log output
Rack::QueryParser::QueryLimitError
Error Message: total number of query parameters (6313) exceeds limit (4096)
If you ever happen to be in the same position, this is how to increase the limit of allowed query parameters:
# config/initializers/rack_query_parser.rb
Rack::Utils.default_query_parser = Rack::QueryParser.make_default(100, params_limit: 10_000)
Posted by Michael Leimstädtner to makandra dev (2025-12-11 14:10)