在 Joomla 4 On the test environment，When installing languages，The following error will pop up：
Error connecting to the server: 303
Invalid URL
Unable to find install package.
If you pass through the Extensions page “Install from Web” To install Extension，The following error will occur：
An error has occurred.
utf8_decode(): Argument #1 ($string) must be of type string, array given
Although it is intuitive that this problem is related to the abnormality of Joomla itself to open the URL，But I can’t find the crux，Nothing was gained from crawling on the Internet。Try to view all extensions of php.ini today，Determine if it may be related to URL or SSL，Just enable the Extension to see，Lucky，Found the key component-curl.dll。
◎ Search in php.ini “extension=curl”，Put the previous “;” Annotation deletion，Restart Apache。
After comparing the settings of the old environment，Curl is indeed enabled，It’s just that I will indicate that this is for BookStack system，So I didn’t enable it in the new environment，Now it seems that both BookStack and Joomla need to be used，And I mistakenly thought that only BookStack needed it。
