Writing file denied

Question

I am getting an error writing a file, that is driving me crazy.
I have an C# netcore 5 application running on RH Linux.
I mounted an shared folder (windows) using: sudo mount -t cifs -o username=MyDomainUsername,password=MyDomainUsernamePassword,domain=MyDomain,dir_mode=0777,file_mode=0777 //ipv4_from_destination/Reports /fileshare/Reports
Then I run the app, using just ./WebApi --urls=http://+:8060
The read/write test executes the following steps:

1. Create a text file.
2. Write the text file.
3. Delete de text file.
4. Creates a directory
5. Creates a text file inside that directory
6. Writes the text file
7. Deletes the text file
8. Deletes the directory.

Now the problem:

1. The text file is created
2. The write operation fails.

Where goes part of the log:

Creating file: /fileshare/Reports/test.616db7d1-07fb-4599-a0cf-749e6a8b34ec.tmp...Ok
Writing file: /fileshare/Reports/test.616db7d1-07fb-4599-a0cf-749e6a8b34ec.tmp...[16:22:20 ERR] ID:87988856-a765-4474-9ed9-2f04aef35771 PATH:/api/about ERROR:System.UnauthorizedAccessException:Access to the path '/fileshare/Reports/test.616db7d1-07fb-4599-a0cf-749e6a8b34ec.tmp' is denied. TRACE:   at System.IO.FileStream.WriteNative(ReadOnlySpan`1 source)
   at System.IO.FileStream.FlushWriteBuffer()
   at System.IO.FileStream.FlushInternalBuffer()
   at System.IO.FileStream.Flush(Boolean flushToDisk)
   at System.IO.FileStream.Flush()
   at System.IO.StreamWriter.Flush(Boolean flushStream, Boolean flushEncoder)
   at System.IO.StreamWriter.Flush()
   at WebApi.Controllers.ApplicationController.TestFileSystem(String folder) in xxxxxxx\WebApi\Controllers\ApplicationController.cs:line 116

What I discovered so far:
I can create and delete the files and directories.
I cannot write to files.

Can someone give me an hint on this?

Answer 1

Solved using the cifs option nobrl