Okay, I removed all dependencies both from system and from environment (pip-
installed): QScintilla, PyQt and sip and installed them solely via pip and it works 
now! Thank you for pointing that out!

Just uninstalled the distribution provided packages and installed the pip wheels 
with the latest versions and everything is working fine.

Note: In order to switch from distribution provided packages to the pip provide 
ones, it is essential to uninstall the distribution ones first.

Just tested your issue on my Fedora 25 VM after an update and eric starts just 
fine. My version numbers are as follows.

Python     3.5.2
Qt         5.7.1
PyQt       5.7
sip        4.18.1
QScintilla 2.9.3
WebKit     538.1

Will now test with pip wheels (after uninstalling the distribution provided 
packages first).

I'd like to add some pip freeze to allow easier debugging:

PyQt5==5.7.1
QScintilla==2.9.4

I used pip-provided wheel to install PyQt5 (yet, it is possible since 5.6+, 
yippee!)

Thank you for the great piece of software! I am using Fedora 25 and the newest 
Eric6. It crashes on start since my last system update. I suspect a newest 
version of python3 and installed PyQt5 (Riverbank) dependencies to be responsible 
for the crash (it worked well before the update). So starting from system 
details:

$uname -a 
Linux - 4.8.15-300.fc25.x86_64 #1 SMP Thu Dec 15 23:10:23 UTC 2016 x86_64 x86_64 
x86_64 GNU/Linux


$python3 -V
Python 3.5.2


$eric6
Segmentation fault (core dumped)


$whereis eric6
eric6: /usr/local/bin/eric6


$cat /usr/local/bin/eric6
#!/bin/sh

exec "/bin/python3" "/usr/lib64/python3.5/site-packages/eric6/eric6.py" "$@"


$gdb -ex r --args python3 /usr/lib64/python3.5/site-packages/eric6/eric6.py

Thread 1 "python3" received signal SIGSEGV, Segmentation fault.
strlen () at ../sysdeps/x86_64/strlen.S:106
106		movdqu	(%rax), %xmm4

(gdb) py-list
Unable to open <frozen importlib._bootstrap>: [Errno 2] No such file or 
directory: b'<frozen importlib._bootstrap>'


(gdb) py-bt
Traceback (most recent call first):
  <built-in method create_dynamic of module object at remote 0x7ffff7f5a728>
  File "<frozen importlib._bootstrap>", line 222, in _call_with_frames_removed
  File "<frozen importlib._bootstrap_external>", line 906, in create_module
  File "<frozen importlib._bootstrap>", line 577, in module_from_spec
  File "<frozen importlib._bootstrap>", line 666, in _load_unlocked
  File "<frozen importlib._bootstrap>", line 958, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 969, in _find_and_load
  <built-in method __import__ of module object at remote 0x7ffff7fac5e8>
  File "/usr/lib64/python3.5/site-packages/eric6/Preferences/__init__.py", line 
37, in <module>
    from PyQt5.QtWebKit import QWebSettings
  <built-in method exec of module object at remote 0x7ffff7fac5e8>
  File "<frozen importlib._bootstrap>", line 222, in _call_with_frames_removed
  File "<frozen importlib._bootstrap_external>", line 665, in exec_module
  File "<frozen importlib._bootstrap>", line 673, in _load_unlocked
  File "<frozen importlib._bootstrap>", line 958, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 969, in _find_and_load
  <built-in method __import__ of module object at remote 0x7ffff7fac5e8>
  File "/usr/lib64/python3.5/site-packages/eric6/eric6.py", line 280, in main
    import Preferences
  File "/usr/lib64/python3.5/site-packages/eric6/eric6.py", line 378, in <module>
    main()


(gdb)#0 bt
0x00007ffff6ca2fe6 in strlen () at ../sysdeps/x86_64/strlen.S:106
#1  0x00007ffff79f626e in unicode_fromformat_write_cstr 
(writer=writer@entry=0x7fffffffb9e0, str=0x100000bf2 <error: Cannot access memory 
at address 0x100000bf2>, width=-1, precision=-1) at /usr/src/debug/Python-
3.5.2/Objects/unicodeobject.c:2373
#2  0x00007ffff79f6a41 in unicode_fromformat_arg (vargs=0x7fffffffba18, 
f=0x7fffebc1f67d "s module requires API v%d.%d", writer=0x7fffffffb9e0)
    at /usr/src/debug/Python-3.5.2/Objects/unicodeobject.c:2614
#3  0x00007ffff79f6a41 in PyUnicode_FromFormatV 
(format=format@entry=0x7fffebc1f650 "the sip module implements API v%d.0 but the 
%s module requires API v%d.%d", vargs=vargs@entry=0x7fffffffbab0) at 
/usr/src/debug/Python-3.5.2/Objects/unicodeobject.c:2706
#4  0x00007ffff7a3cfbd in PyErr_FormatV (exception=<type at remote 
0x7ffff7d51980>, format=0x7fffebc1f650 "the sip module implements API v%d.0 but 
the %s module requires API v%d.%d", vargs=vargs@entry=0x7fffffffbab0) at 
/usr/src/debug/Python-3.5.2/Python/errors.c:776
#5  0x00007ffff7a3c874 in PyErr_Format (exception=<optimized out>, format=
<optimized out>) at /usr/src/debug/Python-3.5.2/Python/errors.c:793
#6  0x00007fffebc123b5 in sip_api_export_module () at /usr/lib64/python3.5/site-
packages/sip.so
#7  0x00007fffced68a9a in PyInit_QtWebKit () at /usr/lib64/python3.5/site-
packages/PyQt5/QtWebKit.so


From what I see this might be some issues of unmet dependencies and definitely 
some shotcomings in formatting of error messages. Could anybody assist me with 
fixing this up?