diff --git a/runtime/doc/if_pyth.txt b/runtime/doc/if_pyth.txt
index 79b1716..19b8b67 100644
--- a/runtime/doc/if_pyth.txt
+++ b/runtime/doc/if_pyth.txt
@@ -1,4 +1,4 @@
-*if_pyth.txt*   For Vim version 8.2.  Last change: 2021 Nov 12
+*if_pyth.txt*   For Vim version 8.2.  Last change: 2022 Feb 07
 
 
 		  VIM REFERENCE MANUAL    by Paul Moore
@@ -65,7 +65,7 @@
 
 							*python-environment*
 Environment variables set in Vim are not always available in Python.  This
-depends on how Vim and Python were build.  Also see
+depends on how Vim and Python were built.  Also see
 https://docs.python.org/3/library/os.html#os.environ
 
 Note: Python is very sensitive to the indenting.  Make sure the "class" line
@@ -834,6 +834,19 @@
 Raising SystemExit exception in python isn't endorsed way to quit vim, use: >
 	:py vim.command("qall!")
 <
+							*E1266*
+This error can occur when python 3 cannot load the required modules.  This
+means that your python 3 is not correctly installed or there are some mistakes
+in your settings.  Please check the following items:
+1. Make sure that python 3 is correctly installed.  Also check the version of
+   python.
+2. Check the 'pythonthreedll' option.
+3. Check the 'pythonthreehome' option.
+4. Check the PATH environment variable if you don't set 'pythonthreedll'.
+   On MS-Windows, you can use where.exe to check which dll will be loaded.
+   E.g. >
+	where.exe python310.dll
+5. Check the PYTHONPATH and PYTHONHOME environment variables.
 
 							*has-python*
 You can test what Python version is available with: >