diff --git a/runtime/lua/vim/lsp/client.lua b/runtime/lua/vim/lsp/client.lua
index 7692759fb8..f413cc812a 100644
--- a/runtime/lua/vim/lsp/client.lua
+++ b/runtime/lua/vim/lsp/client.lua
@@ -948,6 +948,10 @@ function Client:_supports_registration(method)
   end
   local provider = self:_registration_provider(method)
   local capability_path = lsp.protocol._provider_to_client_registration[provider]
+  if not capability_path then
+    -- If we don't know about the method, assume the client supports dynamic registration for it.
+    return true
+  end
   local capability = vim.tbl_get(self.capabilities, unpack(capability_path))
   return type(capability) == 'table' and capability.dynamicRegistration
 end
@@ -956,7 +960,7 @@ end
 --- @param method vim.lsp.protocol.Method | vim.lsp.protocol.Method.Registration
 function Client:_registration_provider(method)
   local capability_path = lsp.protocol._request_name_to_server_capability[method]
-  return capability_path and capability_path[1]
+  return capability_path and capability_path[1] or method
 end
 
 --- @private
@@ -1250,6 +1254,10 @@ function Client:supports_method(method, bufnr)
     return false
   end
 
+  if required_capability == nil and next(self.registrations[method] or {}) ~= nil then
+    return false
+  end
+
   -- If we don't know about the method, or if it is a self-mapping(method=required_capability)
   -- assume that the client supports it.
   -- This needs to be at the end, so that dynamic_capabilities are checked first.
@@ -1280,9 +1288,7 @@ function Client:_provider_foreach(method, fn)
   local required_capability = lsp.protocol._request_name_to_server_capability[method]
   local dynamic_regs = self:_get_registrations(provider)
   local has_subcap = required_capability and #required_capability > 1
-  if not provider then
-    return
-  elseif not dynamic_regs then
+  if not dynamic_regs then
     -- First check static capabilities
     local static_reg = vim.tbl_get(self.server_capabilities, provider)
     if static_reg then
diff --git a/test/functional/plugin/lsp_spec.lua b/test/functional/plugin/lsp_spec.lua
index b9bbfba7c0..2e68f2cbfe 100644
--- a/test/functional/plugin/lsp_spec.lua
+++ b/test/functional/plugin/lsp_spec.lua
@@ -3419,10 +3419,42 @@ describe('LSP', function()
         }, { client_id = client_id })
         check('workspace/didChangeConfiguration', nil, 'section')
 
+        vim.lsp.handlers['client/registerCapability'](nil, {
+          registrations = {
+            {
+              id = 'unknown-method-id',
+              method = 'unknown-method',
+              registerOptions = {
+                some_opt = 'unknown-dummy-opt',
+              },
+            },
+          },
+        }, { client_id = client_id })
+        check('unknown-method', nil, 'some_opt')
+
+        check('unknown-method-2')
+        vim.lsp.handlers['client/registerCapability'](nil, {
+          registrations = {
+            {
+              id = 'unknown-method-2-id',
+              method = 'unknown-method-2',
+              registerOptions = {
+                documentSelector = {
+                  {
+                    pattern = root_dir .. '/*.foo',
+                  },
+                },
+              },
+            },
+          },
+        }, { client_id = client_id })
+        check('unknown-method-2')
+        check('unknown-method-2', tmpfile)
+
         return result
       end)
 
-      eq(21, #result)
+      eq(25, #result)
       eq({ method = 'textDocument/formatting', supported = false }, result[1])
       eq({ method = 'textDocument/formatting', supported = true, fname = tmpfile }, result[2])
       eq({ method = 'textDocument/rangeFormatting', supported = true }, result[3])
@@ -3457,6 +3489,14 @@ describe('LSP', function()
         { method = 'workspace/didChangeConfiguration', supported = true, cap = { 'dummy-section' } },
         result[21]
       )
+      eq({
+        method = 'unknown-method',
+        supported = true,
+        cap = { 'unknown-dummy-opt' },
+      }, result[22])
+      eq({ method = 'unknown-method-2', supported = true }, result[23])
+      eq({ method = 'unknown-method-2', supported = false }, result[24])
+      eq({ method = 'unknown-method-2', supported = true, fname = tmpfile }, result[25])
     end)
 
     it('identifies client dynamic registration capability', function()