diff --git a/lldb/source/Commands/CommandCompletions.cpp b/lldb/source/Commands/CommandCompletions.cpp
--- a/lldb/source/Commands/CommandCompletions.cpp
+++ b/lldb/source/Commands/CommandCompletions.cpp
@@ -611,6 +611,9 @@
 
   RegisterContext *reg_ctx =
       interpreter.GetExecutionContext().GetRegisterContext();
+  if (!reg_ctx)
+    return;
+
   const size_t reg_num = reg_ctx->GetRegisterCount();
   for (size_t reg_idx = 0; reg_idx < reg_num; ++reg_idx) {
     const RegisterInfo *reg_info = reg_ctx->GetRegisterInfoAtIndex(reg_idx);
diff --git a/lldb/test/API/functionalities/completion/TestCompletion.py b/lldb/test/API/functionalities/completion/TestCompletion.py
--- a/lldb/test/API/functionalities/completion/TestCompletion.py
+++ b/lldb/test/API/functionalities/completion/TestCompletion.py
@@ -736,13 +736,25 @@
         self.runCmd("type synthetic add -x Hoo -l test")
         self.complete_from_to("type synthetic delete ", ["Hoo"])
 
-    @skipIf(archs=no_match(["x86_64"]))
-    def test_register_read_and_write_on_x86(self):
-        """Test the completion of the commands register read and write on x86"""
-
+    def test_register_no_complete(self):
         # The tab completion for "register read/write"  won't work without a running process.
         self.complete_from_to("register read ", "register read ")
         self.complete_from_to("register write ", "register write ")
+        self.complete_from_to("register info ", "register info ")
+
+        self.build()
+        self.runCmd("target create {}".format(self.getBuildArtifact("a.out")))
+        self.runCmd("run")
+
+        # Once a program has finished you have an execution context but no register
+        # context so completion cannot work.
+        self.complete_from_to("register read ", "register read ")
+        self.complete_from_to("register write ", "register write ")
+        self.complete_from_to("register info ", "register info ")
+
+    @skipIf(archs=no_match(["x86_64"]))
+    def test_register_read_and_write_on_x86(self):
+        """Test the completion of the commands register read and write on x86"""
 
         self.build()
         self.main_source_spec = lldb.SBFileSpec("main.cpp")