id summary reporter owner description type status priority component resolution keywords cc component_version os os_version 11388 I suspect fz uses a case-sensitive domain. domain RFC uses case insensitivity for domain Jim Michaels "I suspect fz uses a case-sensitive domain. domain RFC uses case insensitivity for domain. I have been unable to login with fz for about 1 month. hosting company says everything OK. please check RFC and act accordingly. there are multiple domain RFC's and one of them is considered more up-to-date. try this with a web browser for proof (protocol is case-sensitive): FILEZILLA-PROJECT.ORG username@DOMAIN.COM - what does the FTP spec say as to case insensitivity or case-sensitivity for the domain part? also, why is fz compiled with -g (debug symbols)? -s -O2 would speed up the code. if it's of any interest, FileZilla Client ---------------- Version: 3.27.1 Build information: Compiled for: x86_64-w64-mingw32 Compiled on: x86_64-pc-linux-gnu Build date: 2017-08-14 Compiled with: x86_64-w64-mingw32-gcc (GCC) 6.3.0 20170516 Compiler flags: -g -O2 -Wall Linked against: wxWidgets: 3.0.4 SQLite: 3.19.3 GnuTLS: 3.5.13 Operating system: Name: Windows 7 (build 7601, Service Pack 1), 64-bit edition Version: 6.1 Platform: 64-bit system CPU features: sse sse2 sse3 ssse3 sse4.1 sse4.2 avx aes pclmulqdq Settings dir: C:\Users\----\AppData\Roaming\FileZilla\ " Bug report closed normal libfilezilla invalid