Errors after upgrade

[MadHatter]

Hi, I'm receiving the following error after upgrading ProcessWire:

Error: Exception: Method Page::viewable does not exist or is not callable in this context (in /processwire/wire25/core/Wire.php line 349)

#0 /processwire/wire25/modules/Process/ProcessPageView.module(407): Wire->__call('viewable', Array)
#1 /processwire/wire25/modules/Process/ProcessPageView.module(407): Page->viewable()
#2 /processwire/wire25/modules/Process/ProcessPageView.module(143): ProcessPageView->checkAccess(Object(Page))
#3 [internal function]: ProcessPageView->___execute(true)
#4 /processwire/wire25/core/Wire.php(389): call_user_func_array(Array, Array)
#5 /processwire/wire25/core/Wire.php(344): Wire->runHooks('execute', Array)
#6 /home/edinudio/public_html/index.php(214): Wire->__call('execute', Array)
#7 /home/edinudio/public_html/index.php(214): ProcessPageView->execute(true)
#8 {main}
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I uploaded the wire dir into a new directory and changed $wireDir in index.php, however this error appears ont he site now. The new wire dir is accessed via a symbolic link, which is also being used on another ~10 sites. As a test I copied the sybolically linked wire dir into a new directory in the site's folder and pointed to that and it seems to work also, so I'm not sure what exactly is happening.

Has anyone else had issues with either the upgrade process or symbolically linking the wire directory or experiencing diffierent behaviour between similar sites? I've been pulling my hair out over this for a few weeks now.

Thanks.

EDIT: I've created another test symlink and used a different name (this one is called "wiresym", the original is called "wire") and it seems to have fixed the problem. Is there some cracy caching thing going on? I tried deleting the broken symlink and renaming the working one to "wire" but then it started playing up on me again.