diff --git a/src/nvim/api/buffer.c b/src/nvim/api/buffer.c
index 9fd366333d..d0e1c890e1 100644
--- a/src/nvim/api/buffer.c
+++ b/src/nvim/api/buffer.c
@@ -49,7 +49,7 @@
 #include "api/buffer.c.generated.h"
 
 /// Ensures that a buffer is loaded.
-static buf_T *api_buf_ensure_loaded(Buffer buffer, Error *err)
+buf_T *api_buf_ensure_loaded(Buffer buffer, Error *err)
 {
   buf_T *buf = find_buffer_by_handle(buffer, err);
   if (!buf) {
diff --git a/src/nvim/api/vim.c b/src/nvim/api/vim.c
index c753463699..29239f4481 100644
--- a/src/nvim/api/vim.c
+++ b/src/nvim/api/vim.c
@@ -1106,7 +1106,7 @@ Integer nvim_open_term(Buffer buffer, Dict(open_term) *opts, Error *err)
   FUNC_API_SINCE(7)
   FUNC_API_TEXTLOCK_ALLOW_CMDWIN
 {
-  buf_T *buf = find_buffer_by_handle(buffer, err);
+  buf_T *buf = api_buf_ensure_loaded(buffer, err);
   if (!buf) {
     return 0;
   }
diff --git a/src/nvim/eval/funcs.c b/src/nvim/eval/funcs.c
index bdaf4d163d..4c333e593d 100644
--- a/src/nvim/eval/funcs.c
+++ b/src/nvim/eval/funcs.c
@@ -3611,6 +3611,15 @@ void f_jobstart(typval_T *argvars, typval_T *rettv, EvalFuncData fptr)
     const int pid = chan->stream.pty.proc.pid;
     buf_T *const buf = curbuf;
 
+    // If the buffer isn't loaded, open a memfile here to avoid spurious autocommands
+    // from open_buffer() when updating the terminal buffer later.
+    if (buf->b_ml.ml_mfp == NULL && ml_open(buf) == FAIL) {
+      // Internal error in ml_open(): stop the job.
+      proc_stop(&chan->stream.proc);
+      channel_decref(chan);
+      return;
+    }
+
     channel_incref(chan);
     channel_terminal_alloc(buf, chan);
 
diff --git a/test/functional/core/startup_spec.lua b/test/functional/core/startup_spec.lua
index 3b6a14b3a4..490de454c6 100644
--- a/test/functional/core/startup_spec.lua
+++ b/test/functional/core/startup_spec.lua
@@ -936,6 +936,61 @@ describe('startup', function()
                                |
     ]])
   end)
+
+  describe('opening a terminal before buffers are loaded #30765', function()
+    local lines = {} --- @type string[]
+    for i = 1, 50 do
+      lines[#lines + 1] = ('line%d'):format(i)
+    end
+
+    setup(function()
+      write_file('Xsomefile', table.concat(lines, '\n') .. '\n')
+    end)
+
+    teardown(function()
+      os.remove('Xsomefile')
+    end)
+
+    it('sends buffer content to terminal with nvim_open_term()', function()
+      clear({
+        args_rm = { '--headless' },
+        args = {
+          'Xsomefile',
+          '--cmd',
+          'let g:chan = nvim_open_term(0, {}) | startinsert',
+          '--cmd',
+          'call chansend(g:chan, "new_line1\nnew_line2\nnew_line3")',
+        },
+      })
+      local screen = Screen.new(50, 7)
+      screen:expect([[
+        line48                                            |
+        line49                                            |
+        line50                                            |
+        new_line1                                         |
+        new_line2                                         |
+        new_line3^                                         |
+        {5:-- TERMINAL --}                                    |
+      ]])
+      eq(lines, api.nvim_buf_get_lines(0, 0, #lines, true))
+    end)
+
+    it('does not error with jobstart(…,{term=true})', function()
+      clear({
+        args_rm = { '--headless' },
+        args = {
+          'Xsomefile',
+          '--cmd',
+          ('lua vim.fn.jobstart({%q}, {term = true})'):format(n.testprg('tty-test')),
+        },
+      })
+      local screen = Screen.new(50, 7)
+      screen:expect([[
+        ^tty ready                                         |
+                                                          |*6
+      ]])
+    end)
+  end)
 end)
 
 describe('startup', function()