Previously we could do this:
However it is no longer working when you have multiple tags so I am guessing this bug has been introduced with a recent release - or has the format changed?
1 « J'aime »
https://meta.discourse.org/new-topic?category=support&tags=tag1,tag2 works just fine for me 
2 « J'aime »
Looks like it’s only happening in certain categories - there are lots of these errors in /logs:
info:
NoMethodError (undefined method `name' for nil:NilClass)
app/models/topic_list.rb:74:in `preload_key'
lib/topic_list_responder.rb:12:in `block (2 levels) in respond_with_list'
lib/topic_list_responder.rb:9:in `respond_with_list'
app/controllers/list_controller.rb:102:in `block (2 levels) in <class:ListController>'
app/controllers/application_controller.rb:358:in `block in with_resolved_locale'
app/controllers/application_controller.rb:358:in `with_resolved_locale'
lib/middleware/omniauth_bypass_middleware.rb:68:in `call'
lib/content_security_policy/middleware.rb:12:in `call'
lib/middleware/anonymous_cache.rb:355:in `call'
config/initializers/100-quiet_logger.rb:23:in `call'
config/initializers/100-silence_logger.rb:31:in `call'
lib/middleware/enforce_hostname.rb:23:in `call'
lib/middleware/request_tracker.rb:177:in `call'
backtrace:
app/models/topic_list.rb:74:in `preload_key'
lib/topic_list_responder.rb:12:in `block (2 levels) in respond_with_list'
actionpack (6.0.3.5) lib/action_controller/metal/mime_responds.rb:214:in `respond_to'
lib/topic_list_responder.rb:9:in `respond_with_list'
app/controllers/list_controller.rb:102:in `block (2 levels) in <class:ListController>'
actionpack (6.0.3.5) lib/action_controller/metal/basic_implicit_render.rb:6:in `send_action'
actionpack (6.0.3.5) lib/abstract_controller/base.rb:195:in `process_action'
actionpack (6.0.3.5) lib/action_controller/metal/rendering.rb:30:in `process_action'
actionpack (6.0.3.5) lib/abstract_controller/callbacks.rb:42:in `block in process_action'
activesupport (6.0.3.5) lib/active_support/callbacks.rb:112:in `block in run_callbacks'
app/controllers/application_controller.rb:358:in `block in with_resolved_locale'
i18n (1.8.9) lib/i18n.rb:314:in `with_locale'
app/controllers/application_controller.rb:358:in `with_resolved_locale'
activesupport (6.0.3.5) lib/active_support/callbacks.rb:121:in `block in run_callbacks'
activesupport (6.0.3.5) lib/active_support/callbacks.rb:139:in `run_callbacks'
actionpack (6.0.3.5) lib/abstract_controller/callbacks.rb:41:in `process_action'
actionpack (6.0.3.5) lib/action_controller/metal/rescue.rb:22:in `process_action'
actionpack (6.0.3.5) lib/action_controller/metal/instrumentation.rb:33:in `block in process_action'
activesupport (6.0.3.5) lib/active_support/notifications.rb:180:in `block in instrument'
activesupport (6.0.3.5) lib/active_support/notifications/instrumenter.rb:24:in `instrument'
activesupport (6.0.3.5) lib/active_support/notifications.rb:180:in `instrument'
actionpack (6.0.3.5) lib/action_controller/metal/instrumentation.rb:32:in `process_action'
actionpack (6.0.3.5) lib/action_controller/metal/params_wrapper.rb:245:in `process_action'
activerecord (6.0.3.5) lib/active_record/railties/controller_runtime.rb:27:in `process_action'
actionpack (6.0.3.5) lib/abstract_controller/base.rb:136:in `process'
actionview (6.0.3.5) lib/action_view/rendering.rb:39:in `process'
rack-mini-profiler (2.3.1) lib/mini_profiler/profiling_methods.rb:111:in `block in profile_method'
actionpack (6.0.3.5) lib/action_controller/metal.rb:190:in `dispatch'
actionpack (6.0.3.5) lib/action_controller/metal.rb:254:in `dispatch'
actionpack (6.0.3.5) lib/action_dispatch/routing/route_set.rb:50:in `dispatch'
actionpack (6.0.3.5) lib/action_dispatch/routing/route_set.rb:33:in `serve'
actionpack (6.0.3.5) lib/action_dispatch/journey/router.rb:49:in `block in serve'
actionpack (6.0.3.5) lib/action_dispatch/journey/router.rb:32:in `each'
actionpack (6.0.3.5) lib/action_dispatch/journey/router.rb:32:in `serve'
actionpack (6.0.3.5) lib/action_dispatch/routing/route_set.rb:834:in `call'
lib/middleware/omniauth_bypass_middleware.rb:68:in `call'
rack (2.2.3) lib/rack/tempfile_reaper.rb:15:in `call'
rack (2.2.3) lib/rack/conditional_get.rb:27:in `call'
rack (2.2.3) lib/rack/head.rb:12:in `call'
lib/content_security_policy/middleware.rb:12:in `call'
lib/middleware/anonymous_cache.rb:355:in `call'
rack (2.2.3) lib/rack/session/abstract/id.rb:266:in `context'
rack (2.2.3) lib/rack/session/abstract/id.rb:260:in `call'
actionpack (6.0.3.5) lib/action_dispatch/middleware/cookies.rb:648:in `call'
actionpack (6.0.3.5) lib/action_dispatch/middleware/callbacks.rb:27:in `block in call'
activesupport (6.0.3.5) lib/active_support/callbacks.rb:101:in `run_callbacks'
actionpack (6.0.3.5) lib/action_dispatch/middleware/callbacks.rb:26:in `call'
actionpack (6.0.3.5) lib/action_dispatch/middleware/actionable_exceptions.rb:18:in `call'
actionpack (6.0.3.5) lib/action_dispatch/middleware/debug_exceptions.rb:32:in `call'
actionpack (6.0.3.5) lib/action_dispatch/middleware/show_exceptions.rb:33:in `call'
logster (2.9.6) lib/logster/middleware/reporter.rb:43:in `call'
railties (6.0.3.5) lib/rails/rack/logger.rb:37:in `call_app'
railties (6.0.3.5) lib/rails/rack/logger.rb:28:in `call'
config/initializers/100-quiet_logger.rb:23:in `call'
config/initializers/100-silence_logger.rb:31:in `call'
actionpack (6.0.3.5) lib/action_dispatch/middleware/remote_ip.rb:81:in `call'
actionpack (6.0.3.5) lib/action_dispatch/middleware/request_id.rb:27:in `call'
lib/middleware/enforce_hostname.rb:23:in `call'
rack (2.2.3) lib/rack/method_override.rb:24:in `call'
actionpack (6.0.3.5) lib/action_dispatch/middleware/executor.rb:14:in `call'
rack (2.2.3) lib/rack/sendfile.rb:110:in `call'
actionpack (6.0.3.5) lib/action_dispatch/middleware/host_authorization.rb:76:in `call'
rack-mini-profiler (2.3.1) lib/mini_profiler/profiler.rb:373:in `call'
message_bus (3.3.4) lib/message_bus/rack/middleware.rb:61:in `call'
lib/middleware/request_tracker.rb:177:in `call'
railties (6.0.3.5) lib/rails/engine.rb:527:in `call'
railties (6.0.3.5) lib/rails/railtie.rb:190:in `public_send'
railties (6.0.3.5) lib/rails/railtie.rb:190:in `method_missing'
rack (2.2.3) lib/rack/urlmap.rb:74:in `block in call'
rack (2.2.3) lib/rack/urlmap.rb:58:in `each'
rack (2.2.3) lib/rack/urlmap.rb:58:in `call'
unicorn (6.0.0) lib/unicorn/http_server.rb:634:in `process_client'
unicorn (6.0.0) lib/unicorn/http_server.rb:732:in `worker_loop'
unicorn (6.0.0) lib/unicorn/http_server.rb:547:in `spawn_missing_workers'
unicorn (6.0.0) lib/unicorn/http_server.rb:143:in `start'
unicorn (6.0.0) bin/unicorn:128:in `<top (required)>'
vendor/bundle/ruby/2.7.0/bin/unicorn:23:in `load'
vendor/bundle/ruby/2.7.0/bin/unicorn:23:in `<main>'
It works in a category that is top level and a single word, but not in a category that is a sub-category and has a hypen in the name 
These work:
https://forum.com/new-topic?category=admin&tags=tag1,tag2
https://forum.com/new-topic?category=moderators&tags=tag1,tag2
These don’t work: (they are sub-categories)
https://forum.com/new-topic?category=frontend-chat&tags=tag1,tag2
https://forum.com/new-topic?category=frontend-news&tags=tag1,tag2
(Guess it might be worth trying to pass the category ID instead? Is that possible?)
Edit:
Looks like it doesn’t work for sub-categories. I created a new sub-category called ‘test’ - tried it, but it didn’t work. I then moved it out of the parent category and made it a top level category… and then it worked.
1 « J'aime »
So the issue is that the URL works for subcategories and for tags, but not for both subcategories with multiple tags at the same time. Updated the title.
Error example: https://meta.discourse.org/new-topic?title=topic%20title&body=topic%20body&category=support/wordpress&tags=wordpress,blog
It works fine via Ember routing but fails server side (like if open in a new tab).
1 « J'aime »
The same thing is happening here with that link in your post:
Oops
The software powering this discussion forum encountered an unexpected problem. We apologize for the inconvenience.
Detailed information about the error was logged, and an automatic notification generated. We'll take a look at it.
No further action is necessary. However, if the error condition persists, you can provide additional detail, including steps to reproduce the error, by posting a discussion topic in the site's feedback category.
…but on my forum it seems to be when the category is a sub-category vs when it is a top level category. I was just using the category name-btw, not including the parent category name in the URL like you have and it was all working fine previously.
(Not sure I would call it a ‘complex’ URL too mind - its just a new-topic URL with params?)
2 « J'aime »
Looks like it regressed in this commit. PR with fix here:
https://github.com/discourse/discourse/pull/12503
Thanks for reporting this issue @AstonJ 
EDIT: PR is merged.
^^ above example now works on server side.
6 « J'aime »