In your specific version of SQL, there may be different columns returned by the FILELISTONLY command.  Run a FILELISTONLY command in the main window and compare the columns that come...

If there are existing overlapping object names, I'd resolve them -- i.e. rename one of the objects -- as part of the rework.  So that, even if stored in separate...

1 Be sure to specify the schema name on the table, assuming of course that it doesn't change from user to user.

FROM dbo.MYTABLE

2. Make the variable the exact same type...

Here's the revised code.  It should work exactly as written now.

DECLARE @sql nvarchar(max)

IF OBJECT_ID('tempdb.dbo.#restore_filelistonly') IS NOT NULL
    DROP TABLE #restore_filelistonly;
CREATE TABLE #restore_filelistonly (
 ...

Something along the lines below, adjust it as needed to match your environment.  You didn't say anything about changing path names for the files, so I just used the paths...

With the sample data thing, with this one it's...

It seems like you might have a (very) old transaction running.

See what this tells you:

USE tempdb;

DBCC OPENTRAN;

...hope you can work it out.

You really need to provide truly representative sample data if you want a full solution.

I once was getting horribly flawed data from FedEx (missing closing quotes, missing delimiters, etc.; genuinely not expected, given their rep).  They would NEVER fix the data.  We had to...

I think this is right.  Naturally you'll need to confirm for yourself, as I don't have any additional test data.

IF OBJECT_ID('tempdb.dbo.#data') IS NOT NULL
   ...

Could do this with recursion, from right to left, but for now I'll just do a simple cursor loop.  Hopefully that will perform well enough for what you need.  Naturally...

Or just make sure they send a string that is valid for conversion in the language they are using!

If I write '25 dek 2020' in English, then that's my error,...

You will NOT get dup rows from dup values in an IN clause.  Easy enough to verify:

CREATE TABLE #t1 ( col1 int NOT NULL )
INSERT...

Either you to do it by CASTing/CONVERTing one language at a time, or have them include a language code in the file.

You could, though, use CASE so that you could...

You don't have to use replace - the string will be converted (implicitly) to an integer for comparison so any leading/trailing blanks will not affect...