Error & reading external variants from file &

What causes this issue?

Uploading a file with external variants at runtime, or error occurred
while importing variants included in procedure.
Basic information about <DS:DE.CATEXCMD>external variants</>

System Response

The error codes have the following causes:

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

Error codes from CAT_EXTERNAL_VARI_UPLOAD:
01 NO_START_IN_BATCH
02 INVALID_FRONTEND
04 NO_VARIANTS_AVAILABLE
10 CANCELED_BY_USER
EXCEPTIONs from WS_QUERY:
11 INV_QUERY
12 NO_BATCH
13 FRONTEND_ERROR
14 OTHERS
EXCEPTIONS from GUI_UPLOAD:
21 CONVERSION_ERROR
22 FILE_OPEN_ERROR
23 FILE_READ_ERROR
24 INVALID_TABLE_WIDTH
25 INVALID_TYPE
26 NO_BATCH
27 UNKNOWN_ERROR
29 GUI_REFUSE_FILETRANSFER
30 NO_AUTHORITY
31 UNKNOWN_DP_ERROR
32 BAD_DATA_FORMAT
33 HEADER_NOT_ALLOWED
34 SEPARATOR_NOT_ALLOWED
35 HEADER_TOO_LONG
36 ACCESS_DENIED
37 DP_OUT_OF_MEMORY
38 DISK_FULL
39 DP_TIMEOUT
28 OTHERS

How to fix this error?

1 Uploading a file with external variants at
runtime is only possible in an online environment. If
external variants are included in the procedure, they are also
executed in
the background.
2 Uploading a file with external variants at
runtime is only possible in a Windows frontend.
If the procedure includes external variants,
these are also started on other frontends.
4 The variant file imported or contained in the procedure
contains no variants. There must be at least one
variant.
11-14 The EXCEPTIONS from WS_QUERY indicate that it was not possible
to find a path name specified on the computer.
Check the path and file settings on your computer.
30 The executing user does not have the following authorization:
OBJECT 'S_GUI'
ID 'ACTVT'
FIELD '60'
This raises the exception NO_AUTHORITY in GUI_UPLOAD.
21-39 The EXCEPTIONS from GUI_UPLOAD indicate that an error occurred
during
UPLOAD of the variant file, so that no variant
could be started. The standard file name is the
procedure number with the extension .TXT.
Check the path and file settings on your computer.

Error message extract from SAP system. Copyright SAP SE.