正确的代码在这里

Options -Indexes
RewriteEngine On
RewriteBase /

# Exclude certain directories from RewriteRule
RewriteCond %{REQUEST_URI} !^/imgs
# Exclude error pages
RewriteCond %{REQUEST_URI} !^/error\.php
# Custom rules
RewriteRule     ^send-email$        send-msg-ajax.php [NC]
RewriteRule     ^cv$                docs/cv.pdf [NC]

# Language rewrite
RewriteRule     ^([a-zA-z_-]+)$     index.php?lng=$1 [QSA,L]

# Custom error pages
ErrorDocument 403 /error.php
ErrorDocument 404 /error.php

请检查此规则

Options -Indexes
RewriteEngine On
RewriteBase /

# Add a RewriteCond to exclude the "lng" parameter for error documents
RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule ^([a-zA-z_-]+)$ index.php?lng=$1 [QSA,L]

RewriteRule ^send-email$ send-msg-ajax.php [NC]
RewriteRule ^cv$ docs/cv.pdf [NC]

# Custom error pages
ErrorDocument 403 /error.php
ErrorDocument 404 /error.php

我添加了一个RewriteCond条件来检查请求的文件是否不存在
（使用%{REQUEST_FILENAME}！-f）。此条件确保“lng”参数不会附加到错误文档的URL中，例如403错误页面。

就像这样：

#custom error pages
ErrorDocument 403 /error.php
ErrorDocument 404 /error.php

Options -Indexes
RewriteEngine On
RewriteBase /

RewriteRule     ^send-email$        send-msg-ajax.php [NC,L]
RewriteRule     ^cv$                docs/cv.pdf [NC,L]

# except for real files and directories rewrite all requests
# to index.php with lng as query parameter containing URI
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule     ^([a-zA-z_-]+)$     index.php?lng=$1 [QSA,L]