luaotfload: Unsupported UNC path encountered

[John Collins]

On 7/10/24 3:10 PM, Rolf Niepraschk via tex-live wrote:
> Am 27.03.24 um 17:56 schrieb Rolf Niepraschk:
>> I use a TeXLive installation (2024) on a Linux server and distribute it
>> via NFS to Linux/Unix clients and via Samba to Windows clients. On a
>> Windows client I integrate TeXLive as follows:
>>
>> ```
>> net use \\SERVERNAME\texlive /persistent:yes
>> setx PATH "\\SERVERNAME\texlive\current\bin\windows\;%PATH%"
>> ```
>>
>> This gives me access to programs like `lualatex` etc. When I translate a
>> document with lualatex, the LaTeX_class and the LaTeX packages are also
>> found. Unfortunately I get the following error several times:
>>
>>
>> ```
>> luaotfload | db : Font names database not found, generating new one.
>> luaotfload | db : This can take several minutes; please be patient.
>> ...texmf-dist/tex/luatex/luaotfload/luaotfload-realpath.lua:34:
>> Unsupported UNC path encountered.
>> ```
>>
>> With TeXLive 2023 this error did not exist. What is wrong? What can I do?
>>
>> Thanks in advance.
>>
>> ...Rolf
> 
> I answer myself. I have found a solution to the problem. It does not
> eliminate the underlying cause, but is sufficient for me at the moment.
> 
> Instead of using the UNC path directly in the PATH variable, I register
> the network resource and assign it a drive letter (here "Y:"):
> 
> net use /persistent:yes y: \\SERVERNAME\texlive /user:USERNAME PASSWORD
> 
> The PATH variable must be modified as follows:
> 
> setx PATH "y:\current\bin\windows;%PATH%"
> 
> Once this has been done, LuaTeX is again able to correctly create and
> update the font name database.
> 
> Perhaps my advice will be of use to those who have the same problem.
> 
> ...Rolf

Good to know.

One correction: Unlike what Rolf says, the error actually may occur on TeX Live 
2023 as well as 2024, provided that TeX Live 2023 was sufficiently updated. 
Mine was fully updated at the time TeX Live 2023 was frozen.

John