I have had a similar problem that requires me to roll back to 4.1.5 for some of my code. I've tracked it down to the following code where I've using eval to build a procedure from piece parts when constructing a rule network. [They parts don't (necessarily) exist in the same syntactic construct, so I can't build them in the rule macro and have to do it when building the rule network.] It now fails (post 4.1.5) if the the rule actions contain references things to another module. <div id=":144" class="ii gt"> </div>(eval `(lambda ,previous-variable-list (begin ,@(rule-actions rule))) (namespace-anchor->namespace anchor))) The error given is: farmer.ss:26:11: link: module mismatch, probably from old bytecode whose dependencies have changed: variable not provided (directly or indirectly) from module: "C:\Documents and Settings\dwilliams\Application Data\PLT Scheme\planet\300\4.2.0.900\ <div id=":144" class="ii gt">cache\williams\science.plt\3\5\random-distributions\triangular.ss" accessed from module: "C:\Documents and Settings\dwilliams\Application Data\PLT Scheme\planet\300\4.2.0.900\cache\williams\inference.plt\2\0\private\inference-control.ss" at source phase level: 0 in: random-triangular</div> In this case, random-triangular is defined in a required package. I suspect it is something different with namespace-anchor->namespace or something along those lines. Any ideas? Doug <div class="gmail_quote"> On Tue, Sep 8, 2009 at 6:36 PM, Robby Findler <<a href="mailto:robby@eecs.northwestern.edu" target="_blank">robby@eecs.northwestern.edu</a>> wrote: <blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">Do you get the error when you run from outside of DrScheme? Robby <div><div></div><div> On Tue, Sep 8, 2009 at 7:04 PM, Carl Eastlund<<a href="mailto:cce@ccs.neu.edu" target="_blank">cce@ccs.neu.edu</a>> wrote: > The cleanup I did each time involved rm -r of the compiled/ > directories, so the drscheme/ subdirectories were gone as well. > > --Carl > > On Wed, Sep 9, 2009 at 12:21 AM, Robby > Findler<<a href="mailto:robby@eecs.northwestern.edu" target="_blank">robby@eecs.northwestern.edu</a>> wrote: >> Likely the files in compiled/drscheme/ are out of date. Why cm isn't >> bringing them back into sync is unclear to me, but you can at least >> get out of the bad loop by deleting those directories. >> >> Robby >> >> On Tue, Sep 8, 2009 at 6:01 PM, Carl Eastlund<<a href="mailto:cce@ccs.neu.edu" target="_blank">cce@ccs.neu.edu</a>> wrote: >>> Running code in DrScheme from one of my planet development links, I >>> get this familiar error: >>> >>> link: module mismatch, probably from old bytecode whose dependencies >>> have changed: variable not provided (directly or indirectly and at the >>> expected position) from module: >>> "/Users/cce/research/planet/scheme/syntax.ss" accessed from module: >>> "/Users/cce/research/planet/scheme/require-provide.ss" at source phase >>> level: 0 in: provide/contract-contract-id-make-planet-path.62 >>> >>> The usual process to fix this is to recompile the relevant files. I >>> have now twice cleaned out all compiled files from my planet >>> development links and run a full 'setup-plt' to restore them, and the >>> message has not gone away. What could be causing this, if the .zo >>> files are all up to date? >>> >>> Carl Eastlund > _________________________________________________ For list-related administrative tasks: <a href="http://list.cs.brown.edu/mailman/listinfo/plt-dev" target="_blank">http://list.cs.brown.edu/mailman/listinfo/plt-dev</a> </div></div></blockquote></div>